All the different kinds of diamond cuts, and how they’re used in watchmaking

Buffy Acacia

Gemstones have held allure for thousands of years. Whether it’s psychological conditioning or some shared link of DNA between humans and crows, we gravitate towards things that sparkle. The art of cutting gems has a long and winding history, but gemstone faceting in the way we’re familiar with today is actually a relatively recent development which has required advanced science both to conceptualise and to undertake. Whether it’s a diamond-set bezel or huge statement jewel on a watch dial, understanding the process of their manufacturing will only enhance your appreciation for them.

A short background on grinding, cleaving, and faceting

For as long as humans have been carving stone, it’s been apparent that stones of differing hardnesses are the key. A piece of flint, which ranks 7 out of 10 on the Mohs hardness scale, is easily able to mark and carve limestone, which is typically a 4 on the Mohs scale at best. Grinding works in a similar way, taking the dust or chips of a hard stone and purposefully eroding away at something softer. Gemstones don’t always look fantastic straight out of the ground, so grinding and polishing was essential for removing unwanted flaws, leftover host rock, or sharp edges so that the stone’s natural colour could shine through. A cabochon is a stone which has been rounded and polished, with no faceted edges.

Even though grinding and polishing was feasible, it’s incredibly labour intensive. Lapidary workers realised that there was an easier way to clean up stones, and that was by the brutal and somewhat terrifying art of cleaving. Many crystals, including diamonds, have natural planes of cleavage within them, meaning that if you hit them hard enough in a very specific spot, a section will break away and leave a perfectly flat surface. It sacrifices much more of the overall stone, but at a time where diamond-loaded grinding disks couldn’t be mass-manufactured, it was the only way to cut diamonds. It’s also where the term ‘cutting’ stems from, rather than grinding.

Nobody really knows where faceting truly began, but it took off in Europe during the 15th and 16th centuries as the technology for and knowledge became more widespread. Flat surfaces not only allowed you to see inside the stone better, making it easier to judge a stone’s quality, but they also reflected light themselves. As faceting evolved over the next few hundred years, it truly became an art form in its own right. A great gem cutter knows which angles will bring out the best colour and clarity of each gemstone, as all stones have their own refractive indices that determine how light travels through them. Then, as polishing and grinding improved, more complicated cuts became possible without the need for cleaving. Now, here’s some of the different cuts.

Round Brilliant

Any watch purchase with diamonds in the bezel or hour markers has a high chance of featuring the Round Brilliant cut, as it’s by far the most prolific style of diamond cutting. It’s featured in all kinds of jewellery, and is also the common kind of stone chosen for an engagement ring. Before the Victorian period, most diamonds used Rose cuts with very visible, triangular facets. This developed into the Old European cut with a very specific design of 58 facets, greatly increasing reflectivity within the stone, and causing it to sparkle way more.

The modern Round Brilliant cut was engineered in the 1950s and also has 58 (or sometimes 57) facets, essentially refining the Old European cut to have more flash, even when dealing with smaller stones. Diamonds are particularly known for their ‘fire’ as white light gets split up into its visible spectrum by bouncing around the facets, and the Round Brilliant cut makes that fire almost more visible than the stone itself. The advent of the Round Brilliant cut also made smaller, cheaper diamonds more marketable, as customers were more easily wowed by their presence. Round Brilliants have also been modified into countless other Fancy cuts, including the triangular Trillion cut, the teardrop-shaped Pear cut, and the elongated, ovate Marquise cut.

Baguette

The natural crystal structure of a diamond is an octahedron. Of course, by the time a diamond reaches the Earth’s surface it’s usually a bit damaged, and then there’s the consideration that not all stones form in the perfect conditions to stay their default shape, and they rarely form without any flaws at all. One of the early styles of diamond cutting for octahedral diamonds was called a Hogback, which uses two strikes to end up with a long octahedron approximately 1/4th of the original stone’s weight. The Baguette cut is a modification of the Hogback, grinding away the upper point of that octahedron and creating a flat table at its top.

Being straight and rectangular in appearance from the top down, the Baguette cut clearly shows the Art Deco hallmarks of its origin in the 1920s and ‘30s. As such, it was relished in women’s wristwatches from the likes of Cartier and Vacheron Constantin. A Baguette diamond doesn’t have the same sparkle as something like a Round Brilliant, but it will typically be much larger than a Round Brilliant and as such be more impressive when lined up around a watch case. A further development of the Baguette cut is the Emerald cut with its corners faceted to create an octagon when viewed from the top, mimicking the octagonal shape of a naturally-forming emerald crystal.

Fancy

Can you name every shape that can possibly exist? Even if you could, it wouldn’t be a good use of your time. When faceting gemstones, sometimes the rough specimen just doesn’t lend itself to being cut in a traditional way. But that doesn’t mean the full potential of its beauty doesn’t deserve to be realised. A Fancy cut is the name given to any non-standard cut, which can include asymmetrical styles, or simply gems which have been cut to preserve their immense size. After all, if you found a record-breaking diamond of incredible proportions, it would be a shame to lose over 50% of its weight just to become a standard Round Brilliant.

With such strong focus on cut gems, and now in a time when people are overly used to seeing Round Brilliants, cutters have been getting creative. Some of those more avant-garde shapes contain hundreds of cuts across different areas, creating dizzying optical effects, especially those which use concave cuts rather than purely flat facets. Those cuts, sometimes called Fantasy cuts, are laborious beyond belief, and can command huge prices even on affordable gemstones such as amethyst and topaz. Another example with growing popularity is the Pixel cut which makes a gem appear like a low-res video game, as the light bounces across its perfectly-square facets hypnotically. Those kinds of cuts haven’t really made it across to watchmaking yet and are still within the realms of experimental jewellery, but the trends are bound to catch up some time soon.