The winter solstice may be behind us, but the Chicago region is still gripped by wintry gloom. We’re brightening our day with a few images from Gems and the New Science: Matter and Value in the Scientific Revolution by Michael Bycroft. In this book, Bycroft argues that gems were connected to major developments in the “new science” between the sixteenth and nineteenth centuries. As he explains, precious and semiprecious stones were at the center of dramatic shifts in natural knowledge in early modern Europe. They were used to investigate luminescence, electricity, combustion, chemical composition, and more. They were collected by naturalists; measured by mathematicians; and rubbed, burned, and dissolved by experimental philosophers. This led to the demise of the traditional way of classifying gems—which grouped them by transparency, color, and locality—and the turn to density, refraction, chemistry, and crystallography as more reliable guides for sorting these substances. The science of gems shows that material evaluation was as important as material production in the history of science. It also shows the value of seeing science as the product of the interaction between different material worlds.

The images below appear in the book, which is the first extended history of the science of gems as well as a fresh interpretation of the Scientific Revolution.

Gems have a long history in European natural history. Medieval books on precious minerals were organized around the concept of “virtue” (virtus in Latin). This was a wide-ranging concept that included physical and chemical properties as well as moral, medical and spiritual powers. This sounds unscientific to modern ears, but medieval authors had an interest in the evaluation and classification of gems that persists to this day. Granatus is a good example. This stone had the virtue of warding off wasps and flies, according to authors drawing on the work of Albert the Great, a thirteenth-century friar and patron saint of science. This virtue was the basis for tests of the authenticity of garnet, such as the one shown in the image. At the same time, Albert’s category granatus was a step in the direction of the category now known as “garnet.” From Ortus Sanitatis (Mainz, 1491), “De lapidibus,” chap. 58. Courtesy of the Wellcome Collection.

European ideas about gems were transformed by encounters with gem deposits in Asia and the Americas. From the sixteenth century, naturalists began to classify gems into “Oriental” and “Occidental” varieties. This was an evaluative distinction as well as a descriptive one, since “Oriental” stones were seen as harder and better than their “Occidental” counterparts. This seventeenth-century French map shows pearls in the Persian Gulf: “pearls are fished in the sand around these islands,” as per the text at the bottom of the map. Note also the reference to the ancient city of Persepolis, in the upper part of the map. Pearls, no less than Persepolis, were part of early European images of “the Orient.” Courtesy of Bibliothèque nationale de France; photo by Michael Bycroft.

Asian gems defied the European custom of classifying gems by their color. For example, the Latin term saphirus had traditionally been applied to blue stones. Yet these blue stones were mined alongside red and yellow stones that had similar properties. Multiple colors were sometimes found in the same specimens, such as the bicolored sapphires shown in figures 11 through 14. These stones were prized by European collectors—the cut sapphire in figure 15 was part of the French crown jewels from at least 1774. That specimen was examined by Jean-Baptiste Louis Romé de l’Isle, a French naturalist who favored geometry over color in the classification of minerals. Figures 6 through 10 (diamond) and figures 16 through 22 (spinel) illustrate Romé de l’Isle’s crystallography. Diagrams from François-Louis Swebach Desfontaines, Mineralogy (1790), vol. 3, plate 99. Courtesy of the Library and Archives, Natural History Museum, London.

Gem science combined the material worlds of natural history and experimental physics. Robert Boyle was at the forefront of experimental natural philosophy in seventeenth-century England, helping to found the Royal Society of London in the 1660s. He was also a prolific collector of gems. He used his collection to argue that gems were originally formed in a fluid medium, a theory that seemed to account for the anomalies and impurities of gems as well as their regularities. To make the case, Boyle used specimens like the ones shown. Top: Transparent, polished am­ethyst with included goethite needles. Middle: Rock crystal from Bristol, which struck Boyle for its regularity (a six-sided prism terminated by a six-sided pyramid) and its irregularity (opposite sides of dif­ferent lengths, some terminations ending in a line rather than a point, etc.). Bottom: Garnet crystals in a sericite-schist matrix. Boyle took garnet crystals “out of their Wombs” himself, to show that their regular shapes were natural rather than artificial. Objects from the collections of the Natural History Museum, London, BM.58341, BM.48054, BM.1911,34. Photos by Michael Bycroft.

Boyle’s French counterpart was Charles Dufay, a member of the Paris Academy of Sciences until his death in 1739. Dufay was a gem connoisseur at a time when natural-history collecting boomed in Paris. Dufay used gems to show that electricity is a general property of matter, that there are two kinds of electricity (roughly, “positive” and “negative” kinds), and that the optical properties of gems depend on their crystal form. He had an especially large collection of rock crystal specimens, similar to the ones illustrated by his contemporary Antoine-Joseph Dezallier d’Argenville. Figures 1 and 2 are described by Argenville as being “faceted by nature,” an analogy to cut gems. Figures 3 and 4 are “true matrices,” in his words, showing the matter in which crystals form. Figure 5 is a single crystal containing elongated objects that the author compared to straws. From Argenville, Oryctology (1755), plate 3. Courtesy of gallica.bnf.fr / Bibliothèque nationale de France.

Gems were still at the heart of European science deep into the eighteenth century. “Precious stones” was still seen as a natural category of mineral, as shown by the title of this plate in a work completed in 1789. The notion of an “Oriental” gem persisted as well, as in the phrase “rubis et topaze d’Orient.” This notion was enriched by the discovery of diamonds and other gems in South America, which gave rise to the category of a “Peruvian” or “Brazilian” gem. These geographical and evaluative notions may seem archaic, but they went hand-in-hand with new kinds of gem classification: note that the “Oriental” and “Peruvian” stones in the plate each have a characteristic crystal form. From Swebach Desfontaines, Natural History (1789), plate 3. Courtesy of the Library and Archives, Natural History Museum, London.

Physics and natural history were still intertwined in the latter eighteenth century, as they had been in Boyle’s day. Crystallography was a branch of natural history, but it relied on measurements of the density and optical properties of stones. The image shows Romé de l’Isle’s crystallography of garnet, including the elementary or “primitive” form of the stone (fig. 1) and some variants of that form (figs 2, 3 and 4). The specimens illustrated in fig 2 and fig 4 were probably used by the physicist Mathurin-Jacques Brisson to measure the density of garnet. Conversely, Brisson’s density measurements were used by Romé de l’Isle to corroborate his crystallography. From Romé de l’Isle and Gautier d’Agoty, Natural History (1781), plate 26. Courtesy of MINES ParisTech.

The category of gems collapsed around 1800, under the combined weight of physics, chemistry, and crystallography. A gap opened up between the properties studied by mineralogists (such as density and birefringence) and the properties valued by jewelers (such as color and transparency). The gap was bridged by a new generation of gem experts who tried to put gem appraisal on a scientific footing. These experts were familiar with the latest developments in mineralogy, but they had minds of their own. For example, they continued to treat color as a clue to the nature and qualities of gems. The English jeweler John Mawe conceded that there are red diamonds as well as red rubies, but he insisted that the redness of diamonds is always different from that of rubies. He used this principle to make the chart of gem colors shown above. From John Mawe, Treatise on Diamonds and Precious Stones (1813). Courtesy of Bodleian Libraries, Oxford.

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Michael Bycroft is associate professor in the history of science and technology at the University of Warwick. He is the coeditor of Gems in the Early Modern World: Materials, Knowledge, and Global Trade, 1450–1800.

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Gems and the New Science is available now. Use the code UCPNEW to save 30% off when you order from our website.