A chemical and spectroscopic comparison of two purple gem spinel samples, one of them the first reported example of a spinel with a saturated purple color caused predominantly by chromium and cobalt.

Using a multi-step process, Lucent Diamonds has developed a new treatment process for certain natural diamonds that creates colors from pink-purple through red to orangy brown.

An examination of the skull-melting technique used to produce cubic zirconia, first introduced in 1976, as well as the market status of this diamond simulant and information about its production and ...

View the holiday schedule for all GIA locations worldwide.

When microscopic identification is not feasible, FTIR spectra at high resolution (0.5 cm^–1) can distinguish natural and synthetic amethyst.

PDF versions of the GIA Laboratory-Grown Diamond Reports are available on Report Check. Look for an icon in the upper right hand corner. Once downloaded, the report can be printed for your records.

Conch "pearls" are calcareous concretions produced by the Queen conch mollusk, Strombus gigas, which is found in various areas of the Caribbean. Although conch"pearls" occur in a range of colors, the ...

While more people are becoming familiar with lab-grown diamonds, many still don’t know how they are actually made. Learn about the two diamond growth processes, HPHT and CVD.

Reports on a visit to a shell nucleus manufacturer and two pearl farms in northern Vietnam, which is emerging as a notable producer.

GIA researchers report on a new nickel-diffusion treatment used to modify color in spinel and present criteria for identification.

Diamonds have a long history as a premier gemstone—a natural consequence of their beauty, rarity, and superlative physical properties such as extreme hardness. Diamonds that are mined for use as ...

A behind-the-scenes exploration of the Smithsonian's Janet Annenberg Hooker Hall of Geology, Gems, and Minerals.