The author acquired an alluvial rough diamond from Guyana showing unique surficial features that do not appear to have been documented elsewhere.

The first installment of this column explores the potential role of modern-day deep-focus earthquakes on diamond growth.

GIA’s New York laboratory reports on a 15.10 ct (17.47 × 11.53 × 7.94 mm) Fancy Vivid blue cut-cornered rectangular step cut named the De Beers Cullinan Blue diamond.

Nacreous pearls are known to have platelet growth resembling fingerprints or topographic maps, but a less common appearance is nacre with a concentric spiral pattern.

Analysis of a transparent yellow angular crystal inclusion in a Brazilian rock crystal quartz host suggests monazite.

A reported new source of blue zircon in Malawi yields rough material for beautiful finished stones in the gem trade.

The Tokyo lab recently identified a unique localized distribution of cloud-like inclusions in a chrysoberyl.

Remarkable “horsetail” inclusions discovered in a demantoid garnet, while their origin and composition remain under discussion.

One of the more subtle inclusion scenes gemologists sometimes observe in natural diamonds is the presence of crystallographically oriented structural defects known as “internal graining.”

Examines the mining and the internal, spectroscopic, and chemical features of peridot from this deposit, which possesses a rich olive green color and is available in large sizes.

A gemological analysis of blue Burmese sapphires from Mogok, based on a series of field expeditions over the last decade.

Contributes to the mining history of Austria’s Habachtal region, which is believed to be one of the earliest emerald deposits.

The Carlsbad lab received a rhodochrosite cabochon featuring rhomboid-shaped fluid inclusions, causing a four-rayed star.

Unique diamond- and emerald-lensed spectacles from the Mughal Empire were tested in GIA’s New York laboratory.

The first installment of this column discusses the formation of colored stones from the crust-mantle transition and below.

Researchers examine six specimens of banded turquoise, obtained through long-term cooperation of local miners in Zhushan County.