For more than a century, the Four Peaks mine in Maricopa County, Arizona, has produced gem-quality amethyst from crystal-lined or crystal-filled cavities and fractures in a brecciated quartzite host rock.

The GIA diamond cut grading system described here includes the components of brightness, fire, scintillation, polish, and symmetry, as well as weight and durability concerns, into a single overall grade for cut quality for standard round brilliants.

This article compares some of Chatham Created Gems’ synthetic colored diamonds to natural diamonds and explains the results.

In recent years, the obligation to fully disclose all gem treatments has changed from a mere ethical responsibility to a legal one.

This article provides an overview of the history of natural and cultured pearls from Mexico, describes pearl culturing at the Guaymas farm, and focuses on the properties of bead-nucleated cultured pearls from P. sterna.

This article presents information about the CVD process, the history of its development, and properties that differentiate the resulting synthetic crystals from natural diamond.

There is only one known commercial occurrence of gem-quality red beryl in the world: the Ruby Violet (or Red Beryl) mine in the Wah Wah Mountains of Beaver County, Utah.

Pezzottaite, ideally Cs(Be2Li)Al2Si6O18, is a new gem mineral that is the Cs,Li–rich member of the beryl group.

Brown-to-gray and near-colorless single-crystal type IIa synthetic diamonds grown using a chemical vapor deposition (CVD) technique by Apollo Diamond Inc. have gemological properties that are distinct from those of both natural diamonds and HPHT-grown synthetic gem diamonds.

Black and dark gray diamonds from Siberia, Russia, were studied by analytical scanning and transmission electron microscopy.

The stories behind seven strikingly beautiful rare natural diamonds, united in an exhibit at the Smithsonian, are told here.

The heat treatment of corundum involving lattice diffusion of beryllium (Be) at temperatures over 1800°C has become a major issue in the gem trade.

Gemological, chemical, and spectroscopic properties are presented for the first known transparent faceted grandidierite.

Just because you don’t see it, doesn’t mean it isn’t there. Many areas in the jewelry industry—education, gemological research, lecturing, publication, and laboratory and inventory documentation, to name a few—either require or benefit from high-quality photomicrography.

The rare borosilicate poudretteite, a mineral that previously had been identified only as tiny crystals.

High-quality synthetic diamonds created by the Gemesis Corp. are examined and their gemological properties are explicated.

This chart combines a comprehensive listing of the commercially available treatments for the most commonly used gem materials with an indication of the current status of their detectability.

This article chronicles the discovery of primary diamond deposits throughout Canada, whose increasing supply of rough stones will have a growing impact on the world diamond industry.