Madagascar sapphire

Lotus Gemology's E. Billie Hughes looks at the important sapphire producing localities in Madagascar, along with the key gemological features that can help separate them from other sapphire sources.

Madagascar has become one of the world’s top sources of fine blue sapphire in recent times. In addition to beautiful untreated material, increasing numbers of treated stones have appeared in the market. Some have been heated to relatively low temperatures, below 1350°C, to lighten their color. To help separate unheated and heated Madagascar sapphire, the authors performed experiments to document the changes they undergo with low-temperature heat treatment in air, which is an oxidizing atmosphere.

In search of ruby and sapphire on the lost Isle of Madagascar.