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A review of the history of this area, its geology, and the mining methods that have predominated.

This article focuses on Colombian emeralds and gives a detailed explanation of the oiling process as observed by the author.

This article examines the history of the Ouro Preto district as well as the geology of the area and occurrence of the topaz.

Thailand has become the world's major source of gem ruby.

Marketed throughout the world, San Carlos material is often confused with, and sold as, peridot from localities that are better known and documented.

A comprehensive review of the history and geology of Colombian emeralds together with descriptions of some of the most famous gems to come from this locality.