Considers the previously unreported but critical impact of silicon on the coloration of gem quality sapphire.

Recounts the history, geology, and notable localities of diamond mining in Brazil, and outlines plans for future diamond production.

Examines the sources, color, texture, and chemical composition of jadeite from Japanese deposits.

Identifies 13 copper-bearing tourmalines, which have traditionally been assumed to be elbaite species, as liddicoatite.

Describes the occurrence of iridescence, and the role of differential etching, in quartz crystals from India’s Jalgaon District.

Investigates the properties of synthetic zincite produced by industrial kilns in Poland.