A highly saturated purplish pink to red pezzottaite from a new deposit in Madagascar is encountered in Tucson and tested by GIA researchers.

Figure 1. Pleochroism in a 15 ct tanzanite, as seen with the unaided eye through the crown and the pavilion sides and ends. Photo by Wimon Manorotkul. ABSTRACT While virtually all gemological texts ...

To commemorate the 50th anniversary of The Wizard of Oz, Harry Winston created real ruby slippers set with 4,600 rubies. - Courtesy Harry Winston Red is the color of our most intense emotions—love and ...

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Malaya garnets from Bekily, Madagascar, are predominantly pink to pinkish orange, with some stones orange to red. Discovered only in the late 1990s, the majority are intermediate members of the pyrope ...

With the increasing use of radiation to color enhance gemstones, the issue of radioactivity has become a source of concern for gemologists worldwide.

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

Blue diffusion-treated sapphires are becoming more prevalent than ever before. The diffusion technique, which involves the addition of color-causing chemicals during heat treatment, results in a thin ...

The northeastern portion of the state of Minas Gerais, Brazil, contains the world's greatest concentration of complex granitic pegmatites, which are especially noted for the production of gem beryl, ...

Studies concerning the origin of color in gem materials have grown in sophistication in recent years, so that much new information is now available about natural color and its possible modification by ...

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 ...

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.