← New Books Network
New Books Network
Michael Bycroft, "Gems and the New Science: Matter and Value in the Scientific Revolution" (U Chicago Press, 2026)
00:53:45
Loading summary
Transcript38 lines
- [00:00]
A
Ugh. You said you were over him, but his hoodie's still in your rotation. It's time. Grab your phone, snap a few pics and sell it on depop. Listed in minutes with no selling fees. And just like that, a guy 500 miles away just paid full price for your closure. And right on cue.
- [00:18]
B
Hey, still got my hoodie?
- [00:19]
A
Nope. But I've got tonight's dinner paid for. Start selling on depop, where taste recognizes taste list. Now with no selling fees, payment processing fees and boosting fees still apply. See website for details.
- [00:32]
B
New Books Network
- [00:36]
A
hello, and welcome to another episode on the New Books Network. I'm one of your hosts, Dr. Miranda Melcher, and I'm very pleased today to be speaking with Dr. Michael Bycroft about his book titled Gems and the New Matter and Value in the Scientific Revolution, published by the University of Chicago Press in 2026. This book combines a whole bunch of things, right? We're going to be talking about the scientific revolution, right? Capital S, capital R and kind of what that was to extent and how that changed all sorts of ideas and doing that through the idea of gems, which are still very much a category that both scientists are aware of and kind of the rest of us, right, we know what gems are. They're relevant, well beyond laboratories. And yet, strictly speaking, as this book opens with quote, gems do not exist. And that's partially because of things like the scientific revolution that we're going to talk about. So there's science here, there's philosophy, there's art, there's kind of wider societal changes. It turns out by combining gems with the scientific revolution and science more broadly, we can unpack all sorts of intriguing shifts in how people have perceived things and do still now. So, Michael, thank you so much for joining me on the podcast to tell us about your book.
- [01:54]
B
Excellent. Thanks very much for the kind introduction and for the invitation to be here.
- [02:00]
A
Well, I'm very pleased to have you. And in fact, speaking of introductions, could you please introduce yourself a little bit and tell us why you decided to write this book? What sorts of questions motivate this project for you?
- [02:12]
B
Yeah, thanks very much. So, as you've said, I'm Michael. I'm an associate professor in the history of science and technology at the University of Warwick in the uk. I have an unusual career path, I suppose, for a historian. I started out doing physics, of all things, at undergraduate level. I combined that with an interest in history, ended up doing a history of electricity or studies of electricity in the 18th century. So that's what I Spent a lot of my early academic career working on, but I kept stumbling upon gemstones like they just kept popping up. And different primary sources that I was looking at. And the first couple of times I thought, this is just a flesh in the pan. This is an anomaly. It's not particularly interesting. But the more examples I came across, the more I felt that there was a pattern here, that gems seem to be everywhere in early modern European science. I'm thinking early modern in the sense of between about 1500 and 1800, between roughly Columbus and Napoleon, to put it very simply, European. I mainly work on French and British history, so those were the main examples I was looking at. But I found gems elsewhere as well. So they seem like a really intriguing but also overlooked topic. So that was my starting point. As you said in your intro, they're also really versatile. Everyone knows that gems are part of economic life, a part of aesthetic life, a part of everyday life, perhaps even a part of political life. And one thing historians of science do and like doing is joining up science with everything else. And I think historians as well. We're a holistic discipline. We like piecing together different aspects of human life which are usually studied separately. So gem seemed like a really promising case study for a historian of science. As I went further along this path, I decided that they could tell us something new about a broader development and history in general, and also in the history of science, which was materialism, very crudely labeled. So when I started out in this field, materialism, materiality and so on were key terms to the point of being buzzwords. Obviously, gemstones are materials, But I think now more than that, they also seem to give a quite different angle on the topic of the material side of science than I had been familiar with. So initially I thought this was going to be a story about production, about making gems. Historians are familiar with the phrase material production. We have been so ever since Karl Marx made it a key to his theory of history. But the more I read these early scientists, the more I realized that they were just as interested in judging these gems as they were in making them. They wanted to know what a good diamond was and how it differed from a substandard diamond or a medium grade diamond. They wanted to know the difference between a very expensive type of gemstone, like an Oriental ruby, and a less expensive gemstone like a red amethyst. And a lot of their techniques were driven by this desire to judge gems. So material evaluation, it seemed to me, became much more important when I paid attention to gems than it had seen before. So hence the word value in the title of the book. There's another word in the title of the book, another keyword, which is matter. And that's a slightly subtler point. But the broad idea is that we're used to thinking about science in terms of the interaction between the mental world, what goes on in our minds, and the material world. That's a well trodden path for historians of science and technology. But we tend to miss all the interactions between different parts of the material world and how these inform ideas. So there's a big literature on the history of natural history cabinets, for example. One important material entity in the history of science is another literature on the history of instruments, another material object, but not much on the relationship between the cabinets of natural history and the instruments. So I kept finding examples of that kind of blind spot between different parts of the material world. And I found that gems were just a really good example for exploring all those blind spots, or rather filling in those blind spots.
- [06:53]
A
So many interesting things there in that introduction. Thank you very much. Gives us lots of things to discuss further in our conversation, because as you said, right. We are historians that love intertwining things and seeing how they sort of all go together and breaking down some of the silos of ways things have been studied. So can we maybe talk a little bit more explicitly, sort of adding into the things you've laid out so far about this idea of the scientific revolution that we briefly mentioned earlier?
- [07:23]
B
Yes. So that's obviously another key term in the title, possibly the most provocative or controversial term in the title, but it's not meant as a provocation. You might know, Miranda, that there are lots of debates among historians, not just historians of science, about whether we should be using that phrase. I found some evidence to argue in favor of it, some evidence against it. Evidence in favor of it included the fact that different branches of science were really closely related in the study of gems. So there seemed to be a kind of unity to the study of natural knowledge in this period, which had been overlooked. Arguments against it, including the fact that many of the really important changes had happened quite late with regards to gemstones. So it's not like the science of gems was fully formed. And 1704, when Isaac Newton published his book on optics, which is often seen as the endpoint of the scientific revolution, actually, we had to wait for another hundred years almost before something like the modern science of gems emerged. So I found reasons for this concept, reasons against it, but ultimately I chose to include that phrase in the title. Because it's a good shorthand for natural knowledge or precursors to modern science in Europe in the period between about 1500 and 1800s. And that seems to be a natural unit of analysis for talking about gemstones, because there was a way of thinking about gemstones which was quite persistent throughout that period and didn't change a huge, huge amount. I guess there's a slightly more methodological point that I wanted to make. The historians who in the past have used that phrase, the scientific revolution, have often been interested in long term intellectual change. They're interested in how big ideas change over the course of centuries rather than decades. And I definitely wanted to write a book of that kind. I'm not sure if every book I write will be like that, but I definitely wanted to write at least one which was taking a key set of ideas and tracing them over a long period.
- [09:36]
A
Well, this book certainly does that, obviously with much more detail than we will be able to cover in this conversation. But, you know, we're going to do our best to talk about a number of the things we've mentioned so far. So I think the next one I want to go into more detail about is something you mentioned a moment ago around kind of these scientists being interested in not just making gems, but also categorizing them. Right. This is also a period, if we think about the history of science more broadly, where we see all sorts of classification systems coming up. Right. Usually we look at botany, for instance. Right. And determining sort of how everything is related to each other in that sort of sphere. What kind of classification systems are we looking at when we examine gems? Is it the same sort of thing is happening in botany or something different going on? What, what's happening in this area?
- [10:24]
B
Right. I'm glad you mentioned that. That follows on nicely to my answer to the previous question. So your audience might be wondering what exactly was that persisted across this period with regards to gems? And what persisted was, at least, as I argue, what persisted was a certain way of classifying gemstones and of thinking about this whole category, and I call it the TCL scheme. T for transparency, C for color, L for locality. So when your average, your typical European naturalist in this period thought about ruby, for example, first of all, they would place it in the category of transparent gemstones. Then they would place it in the category of colored, of red colored gemstones. And then they would say something about where it came from. Was it an oriental gemstone? Scare quotes around Oriental. Was it an Occidental ruby? Was there a more specific locality from which it was derived. So that TCL scheme emerges in the course of the 16th century and persists right until the end of the 18th century. So there's that. One point I do want to make in the book is that classification didn't start with Carl Linnaeus. So a common understanding of the history of classification is that Cal Linnaeus, the great Swedish botany, invented systematic classification, the art of carefully and comprehensively dividing plants and animals and minerals into groups. I certainly don't want to take away from Linnaeus. But classification schemes for gemstones go all the way back to ancient times, both in the Western tradition and in other traditions. Sometimes you need to do a bit of work to find the classification scheme, but often you can find. Often it's expressed in a way that will be unfamiliar to modern botanists or mineralogists, but you can find people dividing gems into groups and subgroups and sub subgroups right back into ancient types. So classification is not something that only historians of botany and the 18th century should be interested, but everyone. So that's part of the answer. Another part of the answer builds on that word matter. So I mentioned that I was interested in how different parts of the material world interrelate. One way of working it out is to look at how different branches of natural history related to each other. So there's a bit of a tendency among historians and other groups to think of natural history as one thing, to think of the natural history of minerals and of plants and of animals to be more or less the same thing, or at least follow the same historical trajectory. Whereas I found that gems were often an outlier or at least very different from plants. And the study of the science of gemstones are very different from botany and the science of plants. A lot of taking for granted assumptions in the history of botany just don't really work for the history of gemstones. So, for example, for the 16th century, the standard story for plants is that there was a species explosion. All of a sudden there were hundreds, even thousands of new species, new in the sense that they had previously been unknown to Europeans that were suddenly entering natural history books. And that then becomes a driver of bigger intellectual changes if you've got many more species and you need new types of classification scheme. So it'll be nice if that story worked out for gemstones, but it just doesn't. If you look at the natural history texts and 1500 and then those in 1630 and look at the sections on gems, you find the number kind of goes up by five or six and then goes down by five or there's certainly not a species explosion for gemstones. So we just need a completely different explanation in the case of gems for intellectual change in the 16th century. So those kinds of differences between different parts of the natural world is one of the things I want to draw attention to when I talk about matter. I think the 18th century is particularly important. I started my answer by talking about Linnaeus. Clearly, something interesting did happen in the 18th century with regards to classification, but it happened differently for gems than it did for plants. So around the time when Linnaeus is publishing his first really influential classification schemes in the 1730s, you find mineral texts which look like they're doing something similar for gemstones, but once you look under the hood, you see that very little has changed. Like the same three categories are being used. Transparency, color, locality. It's all dressed up in fancy clothes. There's a Latin version of the text, as well as being a French or English version of the text. There are synoptic tables which lay out visually the classification scheme. There are other kind of accoutrements of taxonomy, but the basic division into groups remains the same. So it's only much later in the century that gemstones are reclassified in the way that plants are reclassified earlier in the century. And also, it's not just that gems were too late, they kind of lagged behind the plants. It's also that they were classified in a quite different way. So the key for gemstones was essentially to take them apart, to take them apart by dividing them into sub crystals. So you start with a large crystal of diamond, for instance, and then you subdivide it, you subdivide it again until you end up with a crystal which remains the same no matter how much further you divide it. Similarly, for the chemistry of gemstones, it's only in the very late 18th century when naturalists learn how to divide an emerald into its chemical constituents. So I think it's a good example of this point about different parts of the material world, or what I'm calling trans materialism. The classification of gems was very different to the classification of plants, both in terms of the periodization, but also in terms of the kind of classification that was happening. To realize the future America needs, we understand what's needed from us to face each threat head on. We've earned our place in the fight for our nation's future. We are marines. We were made for this.
- [17:12]
A
Yeah, no, that's very interesting to see the differences there, because as you said, we do know some of these kinds of stories very well. And there is, of Course, then a danger of assuming that it's kind of all like that.
- [17:22]
B
Right.
- [17:22]
A
Which this sort of history helps us avoid when we're talking, though, about these sorts of systems and the way they're being used. Can you tell us more about the people involved in creating or disseminating or discussing these ideas about gems?
- [17:38]
B
Yes. So one answer to that question is the usual suspects. So canonical scientists like Robert Boyle. So I had never expected to discover anything new about Robert Boyle. He's the kind of person that is so well known, so widely revered and widely studied, that you would think that there was absolutely nothing new that a young historian could say about such a person. And yet he has this book called the Origin and Virtue of Gems, which until recently, recently was almost totally overlooked by. By historians of science, in large part, I suspect, because gemstones were almost totally overlooked. So certain canonical scientists look different when we notice that they were studying gemstones. In the case of Robert Boyle, what looks different is that he was a collector. He was not just a collector of books or a collector of ideas or a maker of instruments. He was also a mineral collector. And he used these minerals in a really interesting way. He had a very large collection of gemstones, but each gemstone was different. Each gemstone was unique. It had peculiar properties. He would have an amethyst with a piece of metal that appeared to be running through it. He would have a giant piece of rock crystal which had a huge number of very symmetrical crystals and so on and so forth. So he had these kind of rare and curious individual specimens which kind of brings to mind the idea of a cabinet of curiosity. Right. Your listeners are probably familiar with the notion of a cabinet of curiosity, this early modern staple of natural history and of aristocratic collections. You collect a wide range of stuff. It's all very rare and unusual, and it's meant to be a symbol of the difficulty of knowing the world, the variety of the world, the difficulty of knowing it, the importance of knowing things factually rather than theoretically. But in James, in Boyle's case, sorry, he was using his gems in quite a different way. So he definitely did have a theory. He had a very general theory about the way the universe is structured and the way it functions. He thought that nature consists of nothing but matter and motion. And he was using each of these specimens to support his arguments. They weren't just kind of random curiosities that were meant to defy all expectations. They were confirming his expectations about. About the natural world. So here's someone who we think of as being a very scrupulous empiricist. Also someone we think of as being an instrument builder rather than just a collector of objects. And yet that's only one side of him. There's this whole other dimension to his work which has been kind of overlooked. So there are the usual suspects, like Robert Boyle. I talk about other people your listeners might have heard of, like Antoine Laurent Lavoisier, a little bit on Isaac Newton, Georges Buffon, Rene Rehomeur. But I also talk about a whole range of other figures who are much less well known and certainly not well known to historians of science. Some of them are merchants, some of them are gem cutters, some of them are connoisseurs. Some of these people come from pretty humble origins. So gem cutters were really at the bottom of the pecking order when it came to the hierarchy of the crafts in the early modern period. So it was the gem merchants who made all the money. It was the cutters who supplied the labor and made very little money. So you have the cutters, but also connoisseurs who are often aristocrats or even higher up to social hierarchy. There are certain social groups which I only realized fairly late in the project were really important, and so they don't actually appear in the book. And listeners will be pleased to know that there are other historians who are actively working on them. So Woman is one example. They're often hard to find in the sources, but they're always there in the background. So Robert Boyle's sister, Lady Ranelagh, lived with him for a number of years in London. Unfortunately, we don't have their correspondence because they were living together, but had a really intimate intellectual relationship. And there's some evidence that Boyle was relying on Lady Ranelagh's judgments of her own jewels to do his science of gemstones. I've kind of arbitrarily limited the scope to Europe, especially Western Europe, but there was an awful lot of knowledge that was arriving in Europe on the back of the gemstones that were arriving in Europe. So to give one example, one of the key breakthroughs in early modern Europe for gemstones was ditching this idea that color is the key to gem classification. That turned out to be kind of misleading. And for Europeans, this was a revelation. It was. It was revolutionary. But if you were to speak to a miner in Sri Lanka or ceylon in the 15th century, it would have been kind of obvious to them that color is an unreliable guide to species because they were working in mines where there were gems of very different colors, but which otherwise had very similar properties. They all appeared in the same mine, they all felt the same when you touched them with the tongue. They seem to have roughly the same density and so on and so forth. So there's a very wide cast of characters, which obviously was one aim of the book. As I said at the start, the gems are attractive because they're so versatile and involve so many people. I just wanted to put in another word for the cutters, the gem cutters, just because they were kind of marginalized by 18th century naturalists who sort of dismissed them as having a superficial, very commercial, profit driven view of gemstones. And clearly they were profit driven. On the other hand, often that motive went hand in hand with some pretty deep insights about their natures. And a thing that cutters were really sensitive to was hardness. So if any of your listeners have tried to cut a gemstone, they will know that hardness is kind of impossible to avoid. I've only done this once or twice, but my main experience of cutting gemstones is breaking the machine I was using because the gem was just too hard. I tried a soft gem, the next gem was harder, and I broke the machine. So if you want to cut or polish gemstones, you need to know about their hardness. And hardness is one of those properties which was very marginal in ancient and medieval gem classifications, but which became more and more important over the early modern period and turned out to have a lot in common with much more modern or quote unquote scientific techniques. So hardness was a kind of bridge between pre modern and modern gem classifications. And it was the gem cutters who were on that bridge who had made that bridge.
- [24:44]
A
Yeah, they're definitely worth a mention. I'm glad that they're part of the spread of people that you document in the book.
- [24:50]
B
Right.
- [24:50]
A
As you said, it is the usual suspects, but not just them, which is helpful to give us a perspective of some of the connections being made here. And of course, sometimes, as you mentioned, the people interested in these gems are living in the same house, right, the brother and sister you mentioned. But they're also trading information in written forms too. But they stop at some, some point using lapidaries to do it, even though that was kind of for quite a long time the way in which gems were documented in writing. How, when and why does that stop being the way of doing it?
- [25:22]
B
Okay, yeah, great question. Because one way of getting into this whole topic is to think about the publications, the books and other publications that we use to, to study gems and to. To disseminate ideas about gems. So I have in my hand Something called Pierre Precious Guide Visual A Visual Guide to Precious Stones, published by two authors at the Museum Nationale d', Espanature, the Natural History Museum in Paris, a very generous institution, by the way, for supplying images and other expertise for my book. This came out in 2023. So it's a book about precious stones and it's made up of a whole bunch of chapters and each chapter is about a different gemstone. And it's all framed with this introductory chapter where you learn something about the different criteria for identifying them. You learn something about density, something about double refraction or birefringence, something about the color of gemstones, because that's still part of the picture. So in a way, that is a lipidary. In a way, it is a descendant of ancient lipidaries written by people like Pliny the Elder, or medieval lapidaries written by people like Mabo d' Auvergne or Albert the Great. So there's a sense in which the lapidary as a genre hasn't gone away. It's still with us, and it's still one of the most common ways by which people begin to study gemstones at the same time. Something really dramatic did change around 1800, and what changed was the separation of the lapidary as a genre from other more, let's say scientific genres, like the mineralogical textbook. So prior to about 1800, you find that both kind of books are really the same book. So if you take something like Robert de Bercain, his book History of Gems and stones from 1609. So this was a physician based in Prague at the court of the Holy Roman Emperor. And it was doing two things. It was trying to give a cutting edge classification of gemstones based on the most up to date techniques in natural history and natural philosophy. So it's kind of like a mineralogy textbook at the same time. It was designed for jewelers, it was designed for connoisseurs. It was full of the kind of evaluative language that connoisseurs and jewelers would be using. And you can see these two functions in the title of the book. So the original title was the Natural History of Gems and Stones. That's the English translation of the Latin. It was then translated into French and the French translation, the French title, was the perfect jeweller. The text hadn't changed really a bit. It was a very good translation. It was a different language, but the contents, the ideas were much the same. So the exact same book could have two titles, which to us seem quite different. Around about 1800, you see these two genres separating out. So someone like Rene Juste Awy is right at that juncture. He's a French mineralogist, crystallographer, right at the heart of the Parisian scientific establishments in the early 19th century. In 1801, he publishes his great treat, Mineralogie, or treatise on mineralogy, and that becomes a kind of bible for mineralogists in France and elsewhere for the next 20 years. So that's the textbook. A few years later, the same person, Henas Awi, publishes a treatise on precious stones, which is designed to identify gems once they've been cut. So he's a sort of transitional figure because he's one individual, but he's writing two quite different books for two purposes, two different audiences, whereas previously there was no such distinction. So this whole question of the genre of the libertarie is a nice entry point into bigger changes that were going on in the study of gemstones and I would argue in the study of the natural world more generally.
- [29:41]
A
Yeah, I want to talk about some of those changes happening with the study of gemstones when we're talking about that study, like what sorts of experiments were actually happening. I mean, for example, at the same time we talked about botany, but there's also sort of the rise of physics and chemistry as well as mineralogy, as you've just mentioned. So when we're looking, what did it mean to study gemstones at this point?
- [30:03]
B
I think it meant a huge range of things, which is partly why I wrote the book. I wanted this to be. I wanted gems to be a kind of proxy for science in general, which means covering the full range of disciplines. So I have a chapter on mineralogy, obviously, but I also have a chapter on natural philosophy, which is a kind of more philosophical precursor to physics. I have something, a chapter on something called experimental physics. I have a chapter on natural history. There's a chapter which. Which covers cartography and map making as well. So I wanted to cover. Cover as many different scientific disciplines and in each case I wanted to be kind of faithful to the disciplinary terms that were being used at the time and show that gems were part of the formation of the disciplines. So take experimental physics, usually trace to early 18th century Europe, and in the French case, usually traced to someone called Charles du Fay and another person called Rene Reimer. So they're generally credited with helping to turn this very general thing called natural philosophy into something much more specific that dealt with a specific range of phenomena like light and electricity, magnetism, sound and so on. So this is kind of ground Zero for modern experimental physics. And yet the people involved in it are gem connoisseurs. They have large gem connections. They're part of this emerging Parisian culture of natural history collecting, and they're using those collections to do their experiments. So Charles Dufay, one of these figures, will take out drawers from his natural history collection filled of gemstones. He will take them into the sunlight, expose them to sunlight, then heave them into a dark room, and then observe the stones and see whether or not they glow. And some stones glowed and some stones didn't. And he drew various inferences from that. But he was using the cabinet itself, the hardware of the cabinet, the drawers, to do these quite systematic experiments which we would now associate with experimental physics. So one aspect of these experiments that I really wanted to draw out was the way they combined what we think of as natural history with what we think of as experimental physics. Nowadays, we think of those two things as being very different. So if you're in Europe or Britain, you might associate natural history with something like the Natural History Museum in London, whereas physics, you might associate it with your local physics laboratory or some really big multinational laboratory like CERN and Geneva or Nejaneva. So nowadays we think of these as totally different enterprises, but back in the 18th century, they're very closely related. To do good physics, you needed the materials, the raw materials, and that included having natural history collections. In terms of the results that emerged from these experiments, well, they were very wide ranging, but they included some really important findings for science more generally. So I think most listeners will be familiar with the distinction between positive and negative electricity. Anyone who's used a battery will be familiar with that. Well, that is usually traced to this fellow Charles du Fay in Paris and 1720s and 1730s. How does he make that distinction between positive and negative electricity? Well, he took some of his hardest gems, and then he took some of his softest gems, and he tried to electrify them. And he found that the hard ones were easy to electrify and the soft ones were much harder to electrify. He then builds on that. He brings in other substances. But gems are kind of at the heart of this original distinction between two kinds of electricity. So it's not just that gins are in the mix, and they're definitely not on the margins. They're right at the center. They're often the first choice material for someone who has some hypothesis about the natural world.
- [34:23]
A
Close your eyes, exhale, feel your body relax, and let go of whatever you're carrying today. Well, I'm Letting go of the worry that I wouldn't get my new contacts in time for this class, I got them delivered free from 1-800-contacts. Oh my gosh, they're so fast.
- [34:39]
B
And breathe.
- [34:40]
A
Oh, sorry. I almost couldn't breathe when I saw the discount they gave me on my first order. Oh, sorry. Namaste. Visit 1-800-contacts.com today to save on your first order. 1-800-contacts. My dad taught me a lot, including how easy it is to forget to cancel things. So I downloaded Experian, my bff. Big financial friend. Experian could help me cancel my unused subscriptions and lower my bills, saving me hundreds a year. Get started with the Experian app today. Your big financial friends here to help you save smarter. Results will vary. Not all bills or subscriptions eligible. Savings not guaranteed. $631 a year average savings with one plus negotiations and one plus cancellations paid. Membership with connected payment account required. See experian.com for details.
- [35:21]
B
Experian I have created the most advanced AI soldier.
- [35:26]
A
The wait is over.
- [35:28]
B
Tron now streaming on Disney. We are looking for something, something you've discovered.
- [35:34]
A
Give me something to believe and some
- [35:38]
B
of us will stop at nothing to get it ready. The countdown is complete. There's no going back. Our directive is clear. Hang on, Tron. Ares now streaming on Disney.
- [35:51]
A
Rated PG 13. Yeah, this is really interesting to see how gems are kind of part of, as you said, so many different fields in the science, which obviously kind of makes your point earlier about them being overlooked so much more interesting. One thing, however, that hasn't come up yet in our discussion that I think we probably should, given what is known about gems, sort of amongst those of us who are not scientists today, is when we're thinking about classification, maybe the simplest kind that sort of most people would know is the idea of kind of a precious gem versus a semi precious or a non precious gem. And yet that hasn't really come up yet. So when does that start to happen and how are those sorts of judgments being made within all of this?
- [36:37]
B
Well, the short answer is that they're everywhere. So judgments about the value of gems run all the way through the story, right from Pliny the Elder writing in the first century AD through to Renegius Dehui, this cutting edge crystallographer writing in 1817. So this question of preciousness, of how value the gems are, runs right through the story. It's kind of tempting to think, and I was tempted to think that that would drop out in the 18th century. People think about The Enlightenment as perhaps a period when people distinguish between the way the world really is and the way we want it to be, or distinguish between facts and values. But that's not really what's happened. What you find is that there are lots of new, very sciencey or science looking techniques involving really elaborate measurements and powerful precise instruments. So there is a lot of novelty that looks like a step towards modern science. But if you study the purpose of these instruments or these techniques, you find that often the main driver is to judge gemstones, to decide which gemstones are most precious. Just to give you one example, some of the most precise measurements of density done in the whole of the 18th century, at least in Europe, were part of an effort to distinguish between diamonds from South Asia and diamonds from Brazil. What we now know as Brazil, incredibly precise, which were not repeated for decades to come. This was in the 1740s in England by a man by the name of John Alyco. A paper was published in the Transactions of the Royal Society of London. So it's easy to read his paper and think what an amazing piece of early experimental physics. This is. A precursor to later tables of density. It's an example of science becoming much more coldly rational. But if you read the whole thing and you read it carefully, you find that the whole point of it is to work out whether the Brazilian diamonds are better or worse than the Indian ones. And you find that kind of thing recurring right through the 18th century. Even someone like Hannay Justawi, I mentioned that he had these two books. He had the book on mineralogy, his great textbook, which is very rigorous and scientific and distinguished. And then he had this other book, which is his treatise on gemstones, where he's trying to judge or determine gemstones. So he's got these two different books, but if you read them closely, you find there are all sorts of overlaps between them. Initially I thought that this later book was sort of an afterthought. It's published in 1817. He dies, I think 1821. So it's near the end of his life. So it looks like he's kind of gone into a sort of voluntary retirement and fallen back on this kind of leisurely question of the value of gemstones. But that's not at all the case. He was interested in the value of gemstones right from the beginning. And that was driving a lot of the technical innovations that fitted into his textbook on mineralogy. So the value question runs all the way through. I guess the other part of your question was, what changed? How did the new science of gems change the way gems were judged. Of course, the scientists believe that this will be revolutionary, that they would completely transform the way that everyone else had been judging gems for centuries or millennia. And there's certainly a lot of that kind of triumphalist rhetoric, and there's definitely some truth in it. But things didn't change all that much on the ground for two main reasons. One is that the reasons ordinary people cared about gems remained fairly stable. So in 1800, as in 1500, people were interested in the transparency of gems. They were interested in their bright colors or their dazzling optical phenomena like opalescence or the brilliance of the diamond. They remained interested in the geographical origins of the gems, as per that example of Brazil versus India. So then as now, people value gems partly based on where they come from. So there's an entire set of international institutions today dedicated to the nomenclature of gemstones, which exists because people care about whether it's called a Brazilian tourmaline or whether it's called an African tourmaline or an Asian tourmaline, et cetera. Don't quote me on those, on those precise localities of tourmaline, but you get the picture. So these sort of practical, everyday concerns regarding gems persisted right through. And the other thing that acted as a kind of break on intellectual change was that a lot of the scientist techniques were quite impracticable. They didn't work that well in practice. Crystallography was the prime example. So the whole point of crystallography was to take a stone and then divide it into parts, as I mentioned earlier, and then keep dividing it. You can also do crystallography to identify a gem just by looking at it, without dividing it up. But for that it was, it was best to have an uncut specimen. So if you've got a cut diamond or a cut ruby, it's very hard to use crystallographic methods to identify it. So there was an awful lot that was really important for mineralogical textbooks, but didn't actually work that well in practice. Also, scientists, or at least a lot of them, tended to underestimate the reliability of earlier techniques. So I mentioned hardness earlier on, earlier, earlier on, and hardness turned out to be fairly reliable and was often a way of corroborating all these new fangled techniques. Color is an interesting one as well. So even in the early 19th century, there were plenty of jewelers and connoisseurs who thought that color was a good guide to German classification. And rather than ditching it, we should just refine it, just make it more scientific. So rather than identifying a gem based on whether it is red, blue or yellow, rather, we should distinguish and distinguish between different shades of red. The idea was that if someone has seen loads and loads of red gemstones and has a good eye, has trained their eye, then they're going to be actually quite good at distinguishing between, for example, a red ruby and a red amethyst and a red spinel. They're all red, but slightly different shades of red and a good connoisseur can tell the difference. When I have spoken to present day gemologists about this, I've got different responses from different people. So one response is that color is old hats, we just shouldn't be using it, should avoid it. But some others are a bit less skeptical. And definitely color gained a new lease of life in the latter part of the 19th century with the rise of spectroscopy, which is something which I don't cover in the book, but which is also interesting. So there are all sorts of reasons why the scientists ambition of totally overhauling gem appraisal didn't quite work out in practice. What does happen in practice is that there are one or two quite specific new techniques which are applied in quite specific ways. Density is one of those. Double refraction or birefringence is another of those. When I say they were applied in specific ways, I mean that they didn't leave to a complete set of new criteria for valuing gems. What happened was that they were used to confirm or complement existing tests. So there was a famous case, or no longer famous now, but famous at the time, in the late 1810s, in which Hana just awy was involved, where there was a French merchant who turns up in Paris, he has tens of kilos, I think it was 70kg, of what he is calling diamonds. And he wants to make enormous profit by selling these to the great and good of French society. It turns out that someone smelled a rat. It was claimed that in fact these were Brazilian Topaz rather than diamonds. He had bought them for a very low price. The whole thing went to court. There was a massive trial in which Oui was called in to be the expert witness. And in that case, Oui pulled out this whole arsenal of new mineralogical techniques to demonstrate at least to his satisfaction, that these were not diamonds. They were indeed Brazilian topaz. Why do I give that example? Partly because I think it's a cool example and I was really pleased to find it in the archives. But also because that whole distinction between Brazilian topaz and a diamond was not invented by a we. It wasn't invented by a scientist. People have been talking about diamond and Topaz for centuries before this and distinguishing between them. They'd also been talking About Brazilian stones vs. Peruvian stones vs. Asian or Occidental or Oriental stones. What was new was the introduction of double refraction and density to confirm the instincts of jewellers.
- [46:25]
A
That's a cool combination of sort of ancient knowledge and new science that brings together really a whole bunch of things you discuss throughout the book and of course our conversation too. So that might be a good place to conclude. Unless there are any other key takeaways you want to mention you hope readers get from all of this.
- [46:43]
B
Well, I guess it depends on the audience. So for scholars of early modern science or historians of science, I think that the one thing I would really like to push is this notion of trans materialism that we need to think about how gems related to plants, how merchants were rating to artisans, how cabinets of natural history related to instruments if we really want to understand how science evolves in the long term. I've often spoken to gemologists about this project, and my main message to gemologists is that gemology is even more important than most gemologists imagine. So it's a window onto much wider human events. In my case, I'm a historian, so I'm talking about historical events. It's a window onto wider changes in the sciences. It's a window on to wider economic and social and political changes. So there's a huge amount of work still to be done. I've really only scratched the surface of the history of gemstones. So it's not just this niche topic for people who care about gemstones, it's a window onto lots of other things. And I guess for general readers, the main point I want to get across is about the function of science and technology. So it's not just about making stuff, it's often about judging stuff. Whether it's gemstones, whether it's air quality, food quality, land quality. A huge amount of modern science is dedicated to saying that this is good or this is bad, which is kind of counterintuitive because that's not what we usually associate science with. The reason this is important is because obviously scientists can't make these judgments on their own. So we need to have ways of integrating the fancy techniques of assayers and gemologists and medical tectors integrating those techniques with non scientists intuitions or understandings about what is good and what is bad. So science is about quality and about judgment, but it's not the only source of these judgments.
- [48:52]
A
Yeah, I think that's a very important point applicable to quite a wide audience. So a good place then to draw our discussion to a close. Leaving me to just ask what you might be working on now that this book about gems and science is done.
- [49:05]
B
Well, initially I thought once I'm done with this, it's taken so long, I thought, I'm done with gems and I don't want to be pigeonholed as the gems scholarly. So I'm going to move on to something completely different. But now that it's out and I like the product, I'm definitely going to stick with gems, but I am going to move kind of sideways. So this book ends in about 1830 and it's mainly about Europe. I'm really interested in what happened in the following two centuries right up to the present. And I'm interested in what was happening outside Europe and especially how this European tradition of gem science, which I try to uncover in the book, how that was exported to other parts of the world. So I'm originally from the South Pacific, from Aotearoa, New Zealand, where there are some, or at least one very culturally and economically important gemstone, which is New Zealand jade or ponamu, which was very important to Maori people, indigenous people of Aotearoa, very important to them for centuries before Europeans arrived. Then Europeans arrive and bring with them this whole body of beliefs and techniques about gemstones. So I'm curious about how that tradition was adapted, how it was transformed when it arrived in new places. And the reason I think New Zealand jade is particularly interesting, it's not just because I'm from there, it's partly that, but it's not just that. It's also because it's a kind of mirror image of diamonds. So it's got completely different material properties. Diamond is very hard, but not very tough, whereas Ponemoo or New Zealand jade is extremely tough, but not that hard. Diamond tends to occur in very small quantities, whereas ponamu can occur in enormous boulders. Diamond traditionally has been part of cultures which were metal based, which had access to metals for tools and so on, whereas pre colony moldy culture didn't have access to metals. And yet Ponemoo had many metallic properties, like in many ways it's just as tough as steel. So this was a completely new kind of case for European naturalists, new in terms of its material properties, new in terms of the culture that it was embedded in. So I'm curious about how European naturalists adapted to that, with the background project being to think about how European scientists in the present should be adapting their techniques to new places, including former settler colonies like New Zealand.
- [51:43]
A
Well, that certainly sounds very intriguing. So best of luck with that investigation. And of course, while you're doing it, listeners can read the book we've been talking about titled Gems and the New Matter and Value in the Scientific Revolution, published by the University of Chicago Press in 2026. Michael, thank you so much for joining me on the podcast.
- [52:03]
B
Thanks for all your amazing question.