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 ...

Figure 1. This emerald contains a brown crystal of the rare mineral parisite. There is also an oil-filled cavity showing a blue and orange flash effect, along with two large trapped gas bubbles. This ...

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 ...

Gem-quality synthetic or laboratory-grown diamonds are more available in today’s jewelry marketplace than ever before, causing both interest and concern about lab-grown diamonds and whether ...

In November 2022, a parcel of 24 approximately 0.5–1.2 ct spinel crystals, described as cobalt-diffused, were obtained directly from a treater by the research team at GIA in Bangkok. Of these, seven ...

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 ...

Diamonds are known for their hardness – their ability to resist scratches and abrasions. But diamonds are not impervious to damage, since their hardness is uneven along different crystal directions.

This raspberry-and mint-colored tourmaline—nicknamed the “Steamboat”—is one of the world’s finest and most valuable mineral specimens. Photo by Duncan Pay ...

Diamonds are the most amazing of gems. Just as amazing, however, is how natural diamonds reach Earth’s surface. Diamonds are formed 150 to 700 km deep in Earth, and are then carried upward in a rare ...