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A gems dealer's Journal: Interview of Gem Dandy and lapidary historian: Justin K Prim

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Hey Loungers,


How have you all been since the last interview? Hope you enjoyed our interview of Josh Saltzman from Nomad’s. Today, in order to further our understanding of the world of gem cutting, we have decided to go through its history with our pal, the infamous gem dandy and gem philosopher: Justin K Prim.


Justin K Prim in action

Here is the Gem Dandy, Justin K Prim, faceting a stone.


AsiaLounges: Hi Justin, thanks for being with us today! We wanted to invite you upon listening to your presentation on gem history, or rather the history of gem cutting, during the Tucson Show 2018 (USA, Arizona, late January). You went through a lot of interesting points then and we were wondering if you’d be ok to go through this interview with us in order to share this knowledge of yours with the Loungers, our readers! And so, as per usual, our first question is: Who are you Justin K Prim, tell us more about you and how you came to study the history of gem cutting?


Justin K. Prim: Hi AsiaLounges and hello to all your readers. I’m Justin K Prim, an American gem cutter and writer living and working in Bangkok. I learned to cut stones in my late 20’s when I was living in San Francisco and then within a few years I relocated to Scotland and then Bangkok to pursue a gemology degree at GIA. Bangkok’s gem trade captivated me, so I didn’t want to leave and now I’m working as a faceting instructor at a new school, The Institute of Gems Trading, who sent me to Tucson to give my talk. I recently started to write a book on the history of colored stone cutting. It’s a fascinating story that hasn’t been written about too much. My research has gotten me absolutely obsessed with this history and I am excited to being able to share it in the form of last week’s talk and soon a book. As I go through the interview I will share some images from my talk to help illustrate the story that I am trying to tell.


AL: Would you mind taking us through the different steps, pardon the pun, of the Lapidary Arts (Gem Cutting) through the ages? Where, when and why did it start and how did it expand through the world? 


J.K.P.: Well, just to be clear, in my research, I’m making a big distinction between diamond cutting and colored stone cutting. These are two different stories with different technologies and different locations. Also, I am completely avoiding the topic of carving and cabochons and focusing totally on flat faceting. I made all these limitations in my research in order to make the project manageable and interesting to myself and future readers. Also, there have been many books written on diamond cutting and stone carving of antiquity and not many about colored stones faceting, so I wanted to address this lack of written knowledge. Now that I’ve gotten my boundaries clear, I can easily say that the line between diamond cutting and colored stone cutting is blurry and indistinct, especially in the early years. The technology and cutting styles of diamonds have definitely influenced what’s happened in the world of colored stone cutting. The beginning of the story starts in Antwerp in the early 1400’s. History has left us two different images of what is probably the first flat faceting machine. It’s powered by a hand crank and seems to be able to cut two stones at once on a horizontally spinning flat wheel covered in diamond powder and olive oil.


Diagram of early cutting machine

Sketch of an early cutting machine provided by Justin K Prim for the purpose of this interview


One interesting thing to note is that Europeans had the technology to cut flat facets for a few hundred years before, (we have goblets from the 1250’s with flat faceted sides) but in jewelry it wasn’t until the beginning of the Renaissance before man’s imagination (with the help of new technology) caused him to start experimenting with flat facets in jewelry stones.


AL: Can you tell us more about how the lapidary arts came to be and how they got to our shores (Europe and Americas)?


J.K.P.: We can pretty much guess that the first instance of faceting was diamond cutting in India, most likely thousands of years ago, but the techniques of faceting that dominates the world today began in Europe and then spread from there. After the first faceting innovation in Antwerp in the 1420’s it spread around few major cutting centers in Europe: Paris, Prague, London, Venice, Idar-Oberstein in Germany, and also to smaller cutting centers. Over the centuries, the techniques and technology kept advancing and as the discovery of optics was imported from the Middle East and then further developed, gem cutters were able to advance their craft until the perfection of the colored, mirrored stones of the modern era. Faceting techniques spread to America in 1870 but didn’t really get big until the 1940’s. Faceting came to Thailand, in my estimation, sometime around 1900 from France, and then again in the 1940’s from Holland, which is why we see two different types of faceting machines used in the Thai cutting industry. One thing that has really been interesting to me is following the progression of the machines as they develop through history. We have some incredible drawings made at various points in history and I have spent the last six month going through old encyclopedias and cutting books in an effort to create a timeline of machine history. The most interesting period is probably between the French Revolution and the Industrial Revolution, when the machines came into their modern forms with the ability to quickly, accurately, and repeatedly cut different angles with precision all the way around the stone.


Justin K Prim provided us with this diagram to illustrate the machines that came to be between the French Revolution and the Industrial Revolution


AL: Can you tell us more about the transition between non-faceted material (cabochons) to faceted gems?


J.K.P.: Well historically, all jewelry gems before the 1400’s were cut as domed cabochons or as a totally flat colored stone that could be set in a ring. For me, the interesting thing about the development of faceting is that it’s totally connected to the emerging philosophy of the time. There was a lot of new thought happening in Europe and especially Italy in the early 1400s and they became very interested in the idea of light. Coming out of the Middle Ages and going into the Renaissance, writers of the time often spoke of the light that emerged from the cabochon as a divine light from the heavens. This most likely supported the ancient documents that they were translating from Greek that stated that stones had healing and medicinal properties. I’m currently looking deeper into these ideas for an article I am working on about the simultaneous rise of gemstone faceting and the occult proto-science of Renaissance Europe.


Renaissance philosophers holding geometric shapes that look suspiciously like gemstones.


You also had geometry being developed/rediscovered at the time and also the influence of geometrically-based Arabic art coming to Europe on the Silk Road. All of this had a big impression on the cultural imagination of the time. Lots of new ideas were being developed because there was so many new things happening in Europe at the time. The Renaissance was the defining moment in history when the archaic Middle Ages man is transformed into the free thinking, center-of-his-own-universe, Modern man. It’s a really exciting time in Western history and especially art history so I’m happy that this is the period that incubated faceting culture because I’m forced to study it as I do my research.



AL: Going a little bit back in time if you don’t mind, nowadays, most people only know of the big 4 (Ruby, Sapphire, Emerald and Diamond) as well as an extra one or two (Amethyst, Citrine and Topaz to name only those). What of the rest of the gem world? What were our ancestors using and why? Was there a liking for particular gems other than these? Which were the first gems used?


J.K.P: The first thing that comes to mind is Garnet. There are tons of garnets found in rings more than 2000 years old. Ancient Romans wore garnets in their rings and later in the 1600’s they started mining garnets in Bohemia (now the Czech Republic). Garnets were being exported all over Europe and eventually the world from the cutting workshops in Prague and Turnov. The big four, as you mentioned, were already popular in Renaissance times. You had the Spanish importing lots of Emeralds from their conquest of South America. You had Diamonds being regularly imported to Europe after Portugal made colonies in India. Rubies and Sapphires are seen in much of jewelry of the time though there was no distinction known between Rubies and Spinels, so actually Spinels and Sapphires were very popular. In fact, as gemologist-historians look at “rubies” in royal jewelry, they find that many of them are actually spinels. So many of them are spinels that they are now encouraged to stop going back and pointing out these embarrassing mistakes of history. I would say outside of the big four, plus garnet, the only other stones I’ve regularly seen in jewelry of the Renaissance is types of quarts (amethyst, citrine, and clear rock crystal), pearls, sometimes agates and jasper (the specialty of Germany) and rarely Turquoise. Another old gem worth mentioning is paste which is a type of glass used to make crystal-like simulant jewels with. There were definitely other gems known at the time because we can read about their magical and medical uses in documents of those eras but as far as what I’ve seen in surviving jewelry pieces, the big 4 have always been the big 4.


The evolution of cutting

The Evolution of Cutting - Artwork provided by Justin K Prim


AL: According to your researches, how did gem cutters come to create new cuts? Was it more out of need or was it influenced by certain current of ideas, the emergence of other sciences perhaps?


Cutting styles and evolution

Cutting style and Evolution - Diagram by Justin K Prim


J.K.P: In the beginning, the first “cut” was the Point cut which was the natural octahedral shape of a perfect diamond. Think of a four-sided pyramid sitting on top of an identical upside-down pyramid and then set in a ring. The next obvious step was to cut the top of the pyramid off and make a window or “table” to look into the stone. This was the Table cut. From there, they cut off the corners, then added a few more facets. If you look at the development of stone cuts over about 500 years, from the Point cut of antiquity to the Brilliant cut of the early 1900’s, the evolution is pretty logical. I think the cutters of the various cities were very creative and experimented when they could afford to. For example, the Rose cut became very popular in the 1500’s and most likely was created to be able to use all the pieces of rough gem material that were too flat to be faceted as a table cut.


Rose Cut Diagram

Rose cut Diagram provided by Justin K Prim


This enabled them to be able to use and sell a lot more stones than they could before. The styles of jewelry at the time were undoubtedly reactions to the aesthetics and taste of the powerful churches and courts of Europe because no one else could afford such expensive things. But as any artist knows, the taste of the customer is partially dictated by the talent of the artist, so it’s reasonable to assume that the lapidaries and jewelers designed and created new styles to appeal to their kingly customers and also then created the requests that their benefactors dreamed up. Later on, yes, the science of optics started to dictate how the cutters approached their designs. Isaac Newton wrote Opticks, his treatise on light and color, in 1704 and that started a new era of cuts that would begin to be aware of the optical properties of gems. Still, they really didn’t perfect the technique of making mirrored stones until the end of the 1800’s so if you think about it, between 1420 and 2018, optically aware gem designs are still a relatively new idea.


AL: We know that you are an experience cutter yourself, are you, or have you in the past, created new type of cuts? If not, is it something that you’d like to work on?


J.K.P: One interesting thing about being a cutter in the 21st century is that we have computers to aid our cutting and designing. I haven’t gone out of my way to make any new cuts but one thing I regularly do, as many other modern cutters do, is to tweak pre-existing designs for optimum light return. Thanks to the sciences of optics, crystallography, and gemology from the generations that came before us, it’s easy to use software to determine exactly what kind of cuts will produce what kinds of patterns of light and color in a certain stone. You can now model your cuts in 3D with different lighting conditions and tweak the angles and placements of the facets to get exactly the kind of reflections and optical effects that you want. I am really excited about some of the new software that’s being developed for colored stone cutting right now.


Design By Justin K Prim

Example of an existing diagram that Justin K Prim "Tweaked" in GemCutStudio Beta


I have been in regular conversation with three different people that have software coming out in the next year that will let cutters easily create and model gem designs and optimize their cuts for the best color and reflection. In parallel with that, I am also in awe of the work made by old-school cutters who have decades of experience and create their art on machines that are nearly prehistoric. We are in a unique position in history where we have guys in London doing very high quality cutting on hand-crank machines from the 1800’s with no specific angles or indexes and a guy in Singapore cutting on a modern American-made precision faceting machine who is developing his own software in order to create the most ideal gem cuts that you could imagine [The guy in question is called Rex Guo and is a very talented precision cutter]. I feel pretty lucky to have stumbled into this period of faceting history where it seems that both the past and the future are simultaneously alive and I have the freedom to have conversations with both of them.


AL: I understand you are currently working on a book project, can you tell us more about it?


J.K.P: Well, the idea of the book stems from my desire to understand the art of cutting in all its aspects. I realize now that when I started this project, I didn’t know how deep the story was going to go. There are a lot of aspects! Anyway, what I want to do is to travel to each of the cutting centers that I have identified, in Europe, Asia, and America, because this is where gem cutting has flourished so far. I want to do as much book research as I can at home and get as much of the story of each place as is possible and then supplement the old book knowledge with the living, oral history that the cutters tell today. I want to meet people whose families have been cutting for generations who know things that have never been written down. I want to combine these personal and family stories with old book knowledge to create something that has never been done before. Also, I am collecting and taking as many photos as I can because I think the story of gem cutting needs to be as visual as possible. It also makes the reading more fun. I am currently calling it “A Regional History of Colored Stone Cutting” because that’s exactly what it is; The story of every major stone cutting center in history, told by the people that live and have lived there, accompanied by as many old and new photos, illustrations, diagrams, and paintings as I can get my hands on. I hope it’s going to be fascinating, not only for cutters or jewelers, but for anyone who has an interest in history. So far, I have been able to tell the complete story of the cutting region of Jura, France, near the Swiss border and also the story of the rise of cutting in Sri Lanka. As I mentioned before, I am currently working on an article about the interconnected history of gemstone cutting and the occult philosophies of Renaissance Europe. I’m currently focused on recording Asian cutting history since being located in Bangkok makes it a little easier and cost effective, though my true passion lies in the history of Europe and the beginning of faceting history. I hope to visit the Czech Republic later this year and meet cutters and historians in Prague and Turnov, places that have had a huge impact on the history of cutting, not only in Bohemia but also in Germany and France.


Antique lapidary technology

Early Cutting Machine from Prague in 1609 

Most of these stories have never been written before, at least in English, so I'm excited to work on a project that is fresh even though its steeped in ancient history. I will definitely keep you updated on the project so that you can let your readers know how it goes.

AL: Thanks a lot for your time as well as the wealth of information you delivered today Justin! I am convinced our readers will have loved it! This being said, for those of you who'd want to know more about Justin you can follow him on Instagram or through his website: As for us, we are preparing lots of goodies and cool gem articles so stay tuned and as usual, 

If you liked what you have read so far in our pages and want to support A Gem Dealer's Journal, here is a link to our Patreon's Page.

See you in the Lounges, 




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