The chemical composition of synthetic green sapphire includes copper and aluminum oxide, with the copper being the element that is ultimately responsible for its signature green hue. The process of synthetic sapphire production is an expensive and exacting one; however, the additional obstacles that accompany the addition of copper – and the precision required to achieve the right amount of green tint without compromising the strength or clarity of the crystal are likely responsible for its exclusive use on the Rolex Milgauss line of watches.When synthetic sapphire is manufactured, the material has to “grow” over the course of a period of several weeks. Particles attract to one another, forming layers that fuse together to create a dense and ultra-hard substance. The end result of production is a “boule” – a solid piece of synthetic sapphire shaped like a chunky cylinder, which is then cut and shaped to its necessary dimensions.Due to the high costs of production, most watch crystal manufacturers cut their synthetic sapphire boules in a perpendicular fashion, as to maximize the number of crystals that can be created from a single boule. Although this is entirely unconfirmed, it is rumored that Rolex cuts the boule along a diagonal axis to maximize the clarity and strength of the finished crystal. In addition to complicating the cutting and shaping process itself, cutting the boule along a diagonal axis significantly increases the amount of waste, which further adds cost to an already expensive manufacturing process.Despite not making an appearance until just over ten years ago, the green sapphire crystal has quickly become one of the defining characteristics of the Milgauss line. Its pale green tint possesses no functional advantages over a traditional, clear/uncolored synthetic sapphire crystal; however, the green crystal that is exclusively fitted to the Rolex Milgauss 116400GV is one of the primary reasons that individuals seek out this particular reference. The green crystal is something entirely unique to the Milgauss collection and is not something that is found on any other Rolex watch, past or present.
