Mostly, Epstein covers the same ground that Green and Koskoff did last year--in The World of Diamonds and The Diamond World, respectively. But the time lag has also enabled him to consider, in a brief windup section (published in expanded form in the February Atlantic), whether South Africa's De Beers may be losing its monopoly grip on the market. And Epstein's own penchant for conspiracy theory brings us, among other suggested perfidies, the possibility that Jewish-owned De Beers supplied Nazi Germany with industrial stones during World War II. Otherwise he tells the familiar tale of how De Beers has dominated the diamond business for nearly a century via low-profile accords (affording ""deniability"") with black-ruled states and even the USSR. Rough stones are shipped to London where the captive Central Selling Organization holds take-it-or-leave-it ""sights"" about ten times a year for a select group of dealers from Antwerp, Bombay, New York, Tel Aviv, and other diamond centers. With the able assistance of N. W. Ayer (""a diamond is forever""), De Beers has also tended assiduously to the retail side of the enterprise. As Epstein points out, it's been in everyone's best interests to go along with the ""Syndicate"" since scarcity values are minimal. Synthetics are commercially feasible, and the real things have not measured up either as stores of value (unlike gold) or as inflation hedges. Lately, moreover, development of a rich new source in northwestern Australia (which promises to increase world diamond supplies by 50 percent annually within three years), coupled with the departure of Zaire from the CSO orbit, Israeli stockpiling, a cache of polished gems in the hands of exchange-hungry Russians, and recession-depressed demand (which forced De Beers to more than double its inventory of roughs), has threatened to upset the always-delicate balance of the diamond marketplace. In addition to exposing the industry's make-believe aspects, Epstein tells some fine yarns--about Sierra Leone's pot-holers (who mine by moonlight without sanction from Freetown), the workings of New York's scruffy Diamond Dealers Club, and the unexplained presence of a Soviet geologist at a mountain-top Lesotho mine. Also: an interview with Harry Oppenheimer, who heads the colossus. Creditable if high-key reportage--and the Epstein name, plus the Atlantic exposure, plus publisher promo, will give it an edge, warranted or not, over the Green and Koskoff entries.