Big Sky Country Sapphire: Visiting Montana’s Alluvial Deposits
Documents a visit to the upper Missouri River and Rock Creek sapphire mining areas.
Gemstone Enhancement and its Detection in the 2000s
Advances in technology and increased demand for lower-priced gem materials contributed to the proliferation of new treatments throughout the first decade of the 2000s.
Ruby and Sapphire Production and Distribution: A Quarter Century of Change
During the past 25 years, the corundum market has been transformed from one of medium to high-priced gems to one that encompasses nearly all price ranges.
Dual-Color Double Stars in Ruby, Sapphire, and Quartz: Cause and Historical Account
Examines a form of asterism comprising two six-rayed stars, one white and one that exhibits the stone’s bodycolor. Firsthand accounts and a survey of patent documents reveal that diffusion has been used to create or enhance this optical phenomenon in synthetic and possibly natural corundum since the 1950s.
Insights From Inclusions
Natural gemstones are typically far more valuable than synthetic ones, so being able to identify them correctly is a powerful skill.
Spring 1991 G&G Lab Notes
This section, from the Spring 1991 issue of Gems & Gemology, is a compilation of interesting finds from GIA’s laboratories.
Heat Treating Corundum: The Bangkok Operation
An overview of the potential effects that heat treatment can have on corundum.
Heat Treating Ruby and Sapphire: Technical Aspects
A review of heat treatment methods available for use on natural or synthetic corundum.
Green Sapphire Filled with Glass
Analysis reveals blue lead glass filling in a sapphire that has an overall green bodycolor as a result of the filling’s combination with natural yellow color.