Similarities between natural spinels — with intense blue color — and synthetic material, have led to difficulties in the recognition of the natural stones by traditional methods.

A review of the history of this area, its geology, and the mining methods that have predominated.

The properties of a novel gemological imitation, cobalt glass.

A report on the new synthetic ruby trade-named Ramaura.

This article focuses on Colombian emeralds and gives a detailed explanation of the oiling process as observed by the author.

The history of the Kashmir mines, the beautiful sapphires found there, and the outlook for the future.

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

The discovery and gemological properties of gem-quality friedelite.

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

The lapidary arts of Harold and Erica Van Pelt.

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.

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

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

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

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