Khao Ploi Waen and the Siam ruby

Before Chanthaburi became a cutting and trading hub, the mines at Bo Rai and Khao Ploi Waen fed it: basalt-hosted rubies of a deep, slightly brownish red that the trade called Siam ruby and treated as a benchmark for a century. The local ground is largely worked out, and Thailand now imports rough from Africa and Asia to cut. Khao Ploi Waen, whose name means Hill of Gems, can still be climbed for the view over the old gem fields.