Figure 1. This alexandrite cabochon appears brownish green in fluorescent light (left) and brownish purple in incandescent light (right). The cabochon shows chatoyancy under both forms of illumination ...

This 376.85-carat tourmaline was carved by O. Hansen, using the colors of the tourmaline as part of the design. - Chip Clark, courtesy Smithsonian Institution, National Museum of Natural History ...

Birthstones are a fun, popular and colorful introduction to the world of gemstones. They appeal to audiences around the world regardless of gender, age, nationality or religion. Birthstones carry ...

Greater amounts of colorless sapphire—promoted primarily as diamond substitutes, but also as natural gemstones—have been seen in the gem market during the past decade. In the absence of inclusions or ...

Observations of Oval-, Pear-, and Marquise-Shaped Diamonds: Implications for Fancy Cut Grading Presents findings from observations of oval-, pear-, and marquise-shaped diamonds, laying the groundwork ...

GIA’s laboratories use advanced instrumentation and research to deliver accurate grading, identification, and origin ...

This large Australian light opal cabochon weighs 117.85 carats. Small play-of-color flashes of orange and green predominate in a pinfire pattern, with spots of a more muted blue over a grayish ...

GIA will offer convenient access for colored stone identification and identification and origin laboratory services at the show. Drop off your stones for expert analysis and report services in the ...

Criteria for distinguishing emerald filling substances were investigated. Thirty-nine fillers were divided into six substance categories—three “presumed natural” (essential oils [including cedarwood ...

The AGA conference, held February 6 in Tucson, was attended by 138 participants from 11 countries. The program was diverse and engaging, as evidenced by the audience questions after each presentation.

One of the most famous gems in the world, The Hope Diamond is a 45.52 carat Fancy Deep grayish blue diamond. GIA researchers examined it in 1988. Photo: Chip Clark, courtesy of Smithsonian Institution ...

Secure your spot for the Sept. 7-10 event in Carlsbad, CA CARLSBAD, Calif. – January 27, 2025 – Registration for Converge, the singular gem and jewelry event combining the unique expertise of the ...