GIA is a trusted authority known for its rigorous, objective analysis of both natural and cultured pearls. Learn about how ...

CARLSBAD, Calif. – June 2, 2025 – Beginning later this year, GIA (the Gemological Institute of America) will start using descriptive terms to characterize the quality of laboratory-grown diamonds and ...

Below is the list of recognized holidays when GIA locations will be closed.View the holiday schedule for all GIA locations worldwide.

Large quantities of rubies—both rough and faceted—from a commercially important new source in Myanmar (Burma) have been available on the Bangkok market since 1992. The ruby crystals from the Mong Hsu ...

Diamond color is usually the result of selective absorption of incident white light. The unabsorbed portion of this light is transmitted through the diamond and is interpreted by the human vision ...

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

Both vibrational Raman and FTIR spectroscopy have been widely applied in identifying synthetic and natural beryl (Wood and Nassau, 1968; Schmetzer and Kiefert, 1990; Huong et al., 2010). These methods ...

Yogo Gulch, discovered more than 100 years ago, is one of four major sapphire-producing areas in Montana, United States. Yogo sapphires are known for their uniform, well-saturated blue color; relative ...

The Karowe Diamond Mine in Botswana, owned and operated by Lucara Diamond Corp., has gained international recognition for producing large, high-quality type IaB or coexistence of IaB with IIa diamonds ...

A parcel of sapphire and chrysoberyl from the Ilakaka-Sakaraha deposit in southern Madagascar. Photo by Vincent Pardieu, © GIA. Introduction In July-August 2010 and ...

Figure 1. Glass in a silver brooch, hallmark from 1866. Private collection, photo by Jaroslav Hyršl. Tectites are members of a large group of impact glasses, formed by the collision of a meteorite on ...

Originally published in GemGuide in 2016, this comprehensive series examines the quality factors that influence the value of colored gemstones, with a specific emphasis on the role cut quality plays ...