This chart combines a comprehensive listing of the commercially available treatments for the most commonly used gem materials with an indication of the current status of their detectability.

This article presents the first complete gemological characterization of the historic 128.48 ct Brazilian diamond known as the Star of the South.

Although the Pinctada margaritifera oyster usually is associated with the black pearls cultured in French Polynesia, it also can produce attractive large yellow cultured pearls, among other colors.

Vivid blue, green, and purple-to-violet cuprian elbaites, renowned in the gem trade as “Paraíba” tourmalines, continue to be recovered in small amounts from northeastern Brazil.

For most of the 20th century, the principal source of fine spessartine was the area around the Little Three mine near the town of Ramona in southern California.

Jewelry designer Paula Crevoshay showcases the work of some of North America’s leading lapidaries.

This second major article in a three-dimensional modeling study analyzes fire – the visible extent of light dispersed into spectral colors.

This article chronicles the discovery of primary diamond deposits throughout Canada, whose increasing supply of rough stones will have a growing impact on the world diamond industry.

Chinese freshwater cultured pearls (FWCPs) are assuming a growing role at major gem and jewelry fairs, and in the market at large.

Australia’s Argyle mine has set records for volume since its establishment in 1983, and is additionally noted for its rare pink diamonds.

Gemstone enhancements and their disclosure became the most important gemological issue for the jewelry trade in the 1990s.

Two archeological sites that were discovered recently on the island of Antigua appear to have had flourishing lapidary industries.

Haüyne is a rare mineral and an extremely rare gemstone.

Since 1996, large quantities of yellow to blue sapphires have been recovered from alluvial deposits derived from basaltic rocks in northern Madagascar.

There has been considerable debate in the gem trade concerning the nucleation procedures being used to grow large round Chinese freshwater cultured pearls.

Greenish yellow to yellowish green HPHT-treated diamonds exhibited highly saturated body color, well-defined brown to yellow octahedral graining, and visual evidence of heating, among other characteristics.

Results from spectroscopic analyses of GE POL high-pressure high-temperature (HPHT) annealed nominally type IIa diamonds are presented, and these spectral characteristics are compared with those of untreated diamonds of similar appearance and type.

Lapis lazuli has been mined from the Coquimbo Region of Chile since 1905.

Gemological, chemical, spectroscopic, and microscopic properties of blue-green color-change garnets from a new deposit near Bekily, Madagascar, are given.

Criteria for distinguishing emerald filling substances were investigated.