Jack’s Picks: The Astonishing World of Horological Gem-Setting
There is among watch enthusiasts a tendency to dismiss gem-set watches as purely decorative objects whose primary function is to act as a means of ostentatious display (there is an argument to be made that this is true of quite a few luxury watches, not just those sporting precious stones, but that is another article for another time). This is partly due to history, where gemstones have indeed functioned as a means of displaying wealth and temporal power — made evident by only one look at a collection of crown jewels from any royal court. Gem-set objects worn by heads of state have for thousands of years been both repositories of wealth, and symbols of the right to rule. But there is much more to a high-quality gem-set watch than cost and carat weight.
In watchmaking, gem cutting and gem setting are practiced in the larger context of what are known as the horological metiers d’art, which include not only cutting and setting, but also lacquer work, enameling, engraving and other decorative techniques.
These methods all present their own unique challenges and of them all, engraving and gem-setting may be the oldest. The very first watches were not precision timekeepers, but extremely rare, valuable, and affordable pieces of art from jewelers and engravers, made only available to the very wealthy. As such, over the last five centuries the possibilities of horological gem-setting has followed the evolution of gem cutting, polishing and faceting.
To understand horological gem-setting, it helps to understand how modern cuts have evolved and what purpose they are intended to serve. Gem cutting is not a static art and it has evolved over thousands of years; from the simple display of crystals as found in nature, to the optically sophisticated cuts prevalent today.
One of the most commonly seen cuts is the round brilliant, which has very precisely prescribed attributes. The round brilliant cut represents an attempt to increase the amount of light reflected through the interior of the stone, and specifically to increase the amount of fire, or refracted light, produced by a diamond. The cut is relatively new — it was invented in 1919 by Marcel Tolkowsky and has been refined since.
Seen from the side, a round brilliant diamond has a lower pointed pavilion, an upper crown, and a flat top called, logically enough, a table. The pavilion and crown are cut into flat surfaces called facets and the overall design is intended to maximize the amount of light which a diamond absorbs and then reflects back out the top of the diamond. This property is called brilliance, from which the cut gets its name.
The brilliant cut is one of the most frequently used in diamond jewelry and horological gem-setting, and for good reason — it maximizes exactly the optical properties which make a diamond valuable.
There are other cuts as well, including the rectangular emerald and baguette cut, whose geometry makes them suitable for use in setting gemstones directly adjacent to each other in watch bezels and cases. High jewelry watches may also use pavé set diamonds, a word derived from “pavement” in French. Here, small stones are set adjacent to each other to form a surface which looks, quite literally, like it is paved in diamonds.
Gem cutting and polishing involves removing parts of the raw stone. Diamonds in particular and gemstones in their raw state are not particularly impressive objects, but a diamond cutter’s art is to reveal the hidden potential of a stone while removing as little material as is practical (commercial considerations also guide diamond cutting, as there may be much higher profit potential in several high quality smaller stones than one large stone). Nonetheless, it isn’t unusual for up to 50 percent of the raw weight of a diamond to be removed in the cutting process. The original uncut stone which became the Hope Diamond, or the Tavernier Blue, is supposed to have weighed around 115 carats but was cut down to the 65 carat French Blue, before being cut again into the Hope Diamond, weighing in at about 45 carats.
The thought of discarding up to half of a diamond or other precious stones in pursuit of a final, commercially and artistically viable product may seem hair-raising but the situation is even more demanding in horological gem-setting.
Why is creating a high quality gem-set watch so extremely challenging? To illustrate the difficulties let’s look at one from Rolex: the Rainbow Daytona.
The Rainbow Daytona has become (as so often happens with unusual and interesting Rolex watches) something of a cult object, but it is also an excellent example of superb technical execution.
The bezel of the Rainbow Daytona is set with sapphires in a very precise color gradient. Each stone is adjacent to two other stones which almost match its color but not quite exactly, and as you go around the bezel, the sapphires transition from deep blue to purple to lilac, to scarlet, to glowing sunset orange, lemon yellow and deep green, before returning to blue again.
This means that each sapphire must have a very specific hue, saturation and transparency. They must also have an exact geometry, as each stone sits flush, edge-to-edge with the next. Obtaining the correct radiance and color saturation for each stone in a Rainbow bezel may require discarding up to 90 percent of the original stone — this as well as the need for geometric precision are part of the reason horological gem-cutting and setting is so demanding.
The types of setting used in horology are very similar to those used in jewelry, but come with additional challenges thanks to the requirements for matching in clarity and color, as well as the stringent requirements of case geometry. Most high-end fine watchmaking brands produce high-quality jeweled timepieces, but there are nonetheless some companies with an especially long history as jewelers, including Piaget, Cartier and Chopard. Jaeger-LeCoultre also produces refined high jewelry watches, and is noted for its use of so-called snow setting, in which diamonds of up to ten different diameters are used to pave dials and cases — producing a visual effect like freshly fallen snow.
At its best, horological gem-cutting and setting demands manual skills at least as difficult as those required for hand-making and finishing a watch movement. As with watches overall, it’s difficult to appreciate a well-made gem-set watch from photographs alone. In motion, under shifting light, a gem-set watch comes alive, and is worth closer inspection and greater appreciation from watch enthusiasts — both for their sheer emotional impact, and for the highly developed skills and talents necessary to make them.
