corundum, synthetic corundum.7, gems

A wide-ranging review of the international precious-stone industry during 1911, with particular emphasis on diamonds, their production, prices, cutting, and trade. Kunz notes the continuing rise in diamond and pearl prices despite recent financial depression and discusses efforts to establish the metric carat of 200 mg as an international standard. Detailed accounts cover the major South African diamond mines, including De Beers, Premier, and Jagersfontein, the rapidly developing deposits of German Southwest Africa, Australian and Brazilian production, Canadian occurrences, and the Arkansas diamond field, where development remained limited. A substantial section examines the diamond-cutting industries of Amsterdam, Antwerp, and the United States and the competitive effects of new African production. Other gem materials discussed include emeralds from North Carolina, opal from Australia and the western United States, rhodonite, Montana sapphire, turquoise from Virginia and Nevada, zircon, amber, and jade; New Zealand nephrite (pounamu) receives particular attention, including Māori terminology and its growing export for cutting in Europe. The turquoise section includes chemical analyses and discussion of its mineralogical composition. The report concludes with observations on amber deposits in Russia, pearl fisheries in Ceylon and Australia, Japanese cultured or “made” pearls, and contemporary problems affecting the pearl industry.