This note deals with some gemological applications for a tool well known to microscopists: the first-order red compensator. In gemological microscopy, the compensator can be useful in locating ...

The De Beers Cullinan Blue was the early buzz of the spring 2022 auction season, with the 15.10 ct Fancy Vivid blue step-cut diamond far surpassing Sotheby’s presale estimate of $48 million. Bringing ...

The Republic of Mozambique is located in southeastern Africa along the Indian Ocean. Separated from Madagascar by the Mozambique Channel, it is bordered by Tanzania to the north, South Africa to the ...

The gemological and spectroscopic properties of 52 colorless to fancy light-colored HPHT synthetic diamonds (40 of them colorless or near-colorless) produced by AOTC using either toroid- or BARS-press ...

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 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 ...

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 ...

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 ...

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 ...

Terry Coldham (left) and Jack Wilson (right) each have more than 50 years of experience in Australian sapphire mining and trading. They shared their in-depth understanding of the Australian sapphire ...

Sapphire, rough and faceted, from the Rock Creek deposit in Montana has become one of the pillar gems of American origin in the global colored gemstone market. Over the past 10 years, Potentate Mining ...

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 ...