Thai craftsmen are consider the best cutters in the world and have learnt how to cut in pure precision due to their proximity to Burma, the major source of expensive color gemstones like rubies, sapphires, and jade. Many gemstone source countries like in Burma, Africa, South America, or Sri Lanka have gem cutters but lags years behind Thai cutters. Thai craftsmen are also considered the experts in heat treatment of very expensive rubies and sapphires, which is a very difficult skill to acquire.