Garnet is a generally straightforward gem to cut. It is durable, singly refractive, and takes a beautiful polish. Although inclusions in garnet are regularly easy to spot and remove during cutting, some of the darker varieties, especially from East Africa, will often have silky inclusions throughout the body of the material that cannot be seen in the rough. To be able to see them, one must cut a “window” or a polished flat place on the gem to know if the material is clear of these minute inclusions.
Another factor that relates to the cutting of garnets is the type of geological deposit in which they’re found. The alluvial, or water-worn deposits, of malaya, rhodolite or spessartine garnets will contain solid, rounded off crystals with a frosted surface. In contrast, the mint green garnets of Merelani are often broken off from their host rock, and will contain glassy feathers and fractures from this damage. However, the crystal surfaces of the Merelani mint garnets are clear and easy to see into. Tsavorite garnet rough is often angular and fractured – suggestive of the surface and in siu environment it comes from. The high price of tsavorite, coupled with the irregular shape of the rough, creates a particularly daunting task for cutters. The result is often windowed and asymmetrical cuts on commercial goods, and low yields on finely cut gems.
In a word, garnet is particularly rewarding to cut. When time is taken to create a gem with symmetry, order, and a fine polish, the effects are especially beautiful on a garnet.