Rare optical phenomenon observed in four star quartz cabochons from Brazil.

A fascinating diamond crystal inclusion displaying a transparent, ghost-like appearance is identified in a Faint green diamond.

A lab in Bangkok shares study on color stability in yellow sapphire.

Numerous etch channels are observed in a 5.19 ct type IIa natural diamond.

Unique natural etch pattern and dissolution cavities are observed in a large aquamarine crystal.

A glimpse at the rare gems recently on display at the Natural History Museum of Los Angeles County’s Brilliance: The Art and Science of Rare Jewels exhibit.

Offers the first detailed summary of amber from the Vietnamese island of Phu Quoc and a comparison with Baltic, Dominican, and Burmese material.

Uses gamma-ray spectrometry to directly measure internal radioactivity in green nephrite from deposits in Poland, Russia, Canada, and New Zealand.

GIA’s New York laboratory reports on a 15.10 ct Fancy Vivid blue cut-cornered rectangular step cut named the De Beers Cullinan Blue diamond.

This installment of “Colored Stones Unearthed” explores inclusions in gems—how they form, how they are studied, and what they mean for gemologists and geoscientists.

An examination of 45 gems from the coronation crown of Napoleon III, using nondestructive mobile spectroscopic and gemological testing methods.

Discusses the unusual surface characteristics of ekanite from secondary deposits in Sri Lanka.

Reports on diamonds from Guyana’s alluvial deposits, including mining history and practices.

Two impressive diamonds from Arkansas and Colorado are featured in the Great American Diamonds exhibit at the Smithsonian’s National Museum of Natural History.

The historic discovery of a Maine tourmaline source is celebrated through jewelry designs featuring gems unearthed 50 years ago.