Since 2002, tsavorite and other grossular varieties have been recovered from a primary deposit at Itrafo, a village in the Andrembesoa area of central Madagascar. Twenty-two samples from this locality ...

The soothing soft pink shades of rose quartz appeal to gem carvers and collectors. – Valerie Power, courtesy Arunashi People accept a certain amount of sand, dirt, and dust as ordinary ingredients in ...

Although rarely encountered, blue diamonds are among the most famous, and most distinctive, of fine gemstones. To better understand these unique gems, more than 400 were studied at the GIA Gem Trade ...

In an effort to help you understand the GIA Cut Grading System more fully, and to make the best use of it in your business, we provide these informative charts and booklets that summarize the system, ...

Gem-quality diaspore occupies an important position in the gem market due to its rarity, striking pleochroism, and color-change phenomenon (figure 1). The material’s value depends on these factors. A ...

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 ...

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 ...

Carbon is one of the most important elements on our planet, which led the Geological Society of London to name 2019 the Year of Carbon. Diamonds are a main host for carbon in the deep earth and also ...

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.

Figure 1. A view of the Lombok farm from the shoreline showing the covered area where the operating and harvesting steps are carried out. Photo by Jeffery Bergman. Cultured pearls are harvested from ...

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 ...

Of all the sapphire deposits found in Montana, the richest is in the Rock Creek (Gem Mountain) district. Between 1890 and the 1930s, over 65 tonnes of rough sapphire were recovered from this area and ...