A 1.10 ct Fancy Deep brownish orangy pink round diamond was recently submitted to GIA’s New York laboratory for analysis (figure 1). This diamond was multi-treated—a combination of high-pressure, high ...

One of the greatest concerns with emerald filling is the degree of clarity enhancement such treatment represents. Stones that appear to have excellent clarity with the unaided eye are often revealed ...

Tanzanite is one of the most popular colored gemstones in the world.- Courtesy Tanzanite Foundation ™ Tanzanite is a versatile gemstone that comes in a variety of sizes and cutting styles. Although it ...

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Soon after it was first marketed in 1976, colorless cubic zirconia became the dominant diamond imitation, with current production of approximately 60 million carats per year. Although cubic zirconia ...

Figure 1. Strands of Nigerian beryl in assorted colors. Photo by Kevin Schumacher. During the JCK show in Tucson, GIA had the opportunity to meet up with Amina Egwuatu, founder of Mina Stones. Mrs.

Diamonds have a long history as a premier gemstone—a natural consequence of their beauty, rarity, and superlative physical properties such as extreme hardness. Diamonds that are mined for use as ...

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 ...

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 ...

North America has a long history of natural pearling owing in part to its very diverse and rich freshwater mussel resources. After the Civil War pearl jewelry gained greater popularity in the United ...

Gem inclusions are mineral crystals or cavities filled with fluid and/or gas that occur in a host gemstone. Many gems contain microscopic inclusions (ranging in size from >1 mm down to submicroscopic ...