Documents a trip to the renowned opal fields of Lightning Ridge, Koroit, Yowah, and Quilpie.

Archival research and gemological characterization reveal the true story of this 135.74 ct blue sapphire from the French crown jewels.

This type of pink pyrope garnet, believed to have been mined in Tanzania, shows a distinct color-change phenomenon resulting from its unique chemical composition.

Rare material from Brazil features four-ray stars under point-source light.

A report from the 34th IGC, held in Vilnius, Lithuania in August 2015.

A large fluid inclusion within a demantoid garnet from Madagascar provides insight into the source’s mineralization.

An unfamiliar rough fragment acquired from Madagascar may point toward a new source of grandidierite.

A new type of African chalcedony with the trade name “Aquaprase” shows unique composition and attractive color.

Two blister pearls attached to a host shell believed to have fossilized during the later Pleistocene period and discovered in southeastern Kenya are studied.

A semi-baroque pearl with an unusual radial feature is submitted to the Bangkok lab for testing.

An inclusion outlined by minute graphite crystals within a diamond create an octahedral shape.

Two near-colorless rounds, weighing 3.23 and 2.51 ct, were the largest CVD-grown synthetic diamonds GIA has examined.

The fluorescence of hyalite from Zacatecas, Mexico is examined and compared to material from other locations in GIA’s Tokyo lab.

A Mexican fire agate cabochon’s coloration and structure combines to create an unusual visual effect.

Rare material found as inclusions in quartz is thought to have formed simultaneously with the host.

Under magnification, a round brilliant diamond features a pyrope garnet inclusion in an aesthetically pleasing shape.

A singly refractive inclusion within a yellow sapphire proves to be spinel.

Microscopic and chemical analysis may provide clues to the original source of Montana’s alluvial sapphires and help distinguish them from sapphires with overlapping properties.

An overview of the Winter 2015 Gems & Gemology content.

Examines the origin and nature of tarnish spots in high-purity gold and how they can be avoided.