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.

GIA ensures accurate gemological measurements across its global laboratories through rigorous metrology practices, including systematic instrument calibration, validation from traceable standards, and ...

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 ...

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

The sapphire deposit at Penglai, on Hainan Island, is potentially the largest in China. Gem-quality sapphires, at least one as large as 35.5 ct, have been found in alluvial gravels approximately 2 km ...

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.

To give objects a futuristic look, Art Deco artists used vertical lines and geometric shapes (arcs, circles, triangles, squares, rectangles, etc.) in repetitive patterns. The Chrysler Building in ...