Isolated nitrogen confined to the outer surface of a 0.98 ct diamond causes “yellow skin.”

Fiber-optic light creates a night sky scene in a yellow sapphire from Madagascar.

Unusual natural pink diamonds displaying faint yellow color zoning and strong yellow fluorescence are studied in the Carlsbad laboratory.

Investigates the mineral and chemical compositions and surface morphology characteristics of brown mammoth ivory to identify the origins of its brown color.

Reports on a newly discovered treatment process for producing a deep blue color in natural spinel and proposes identification criteria.

Offers a comprehensive look at a variety of augite from Dong Nai, Vietnam, detailing its formation and gemological characteristics.

A rare example of pink pyrope garnet is examined in the Carlsbad laboratory.

Four atypical bead cultured pearls with variations on two types of nuclei are examined in the Mumbai laboratory.