This article examines the history of the Ouro Preto district as well as the geology of the area and occurrence of the topaz.

The term "alexandrite effect" refers to the apparent change of color in certain minerals from blue-green or greenish violet in daylight to red or reddish violet in incandescent light.

Thailand has become the world's major source of gem ruby.

The discovery and gemological properties of gem-quality friedelite.

The lapidary arts of Harold and Erica Van Pelt.

An examination of the challenges of carving gem-quality opal.

Gamma ray spectroscopy revealed that a packet of spodumene from Brazil was radioactive.

An overview of the many types of gem-quality material, and its inclusions, currently found in Sri Lanka.

How amethyst under certain conditions may turn green rather than the expected citrine-yellow.

An examination of the various simulants of of nephrite and jadeite, and how to separate them from jade.

The cutting of a one-kilo kunzite crystal demonstrates the problems inherent in working with this stone.

Marketed throughout the world, San Carlos material is often confused with, and sold as, peridot from localities that are better known and documented.

A discussion of the techniques important in producing top-quality photomicrographs.

A review of heat treatment methods available for use on natural or synthetic corundum.