Manhattan's Diamond District--West 47th Street and environs- -provides the exotically corrupt milieu for another slick entertainment from the prolific Browne (18mm. Blues, 1993, etc.) A successful freelance who grew up in the retail jewelry business, Mitch Laughton specializes in the recovery of lost, strayed, or stolen gems. In the wake of a spectacular heist that cost an Iranian couple considerable blood and treasure, he's called in--by the insurance company left holding the policy bag--to locate millions of dollars' worth of precious stones that have gone missing. Once on the case, rough-hewn Mitch (who's married to Maddie, a terminally winsome, relentlessly meddlesome, filthy-rich blind woman with impeccable social connections) taps all of his many sources in the Midtown enclave--including the raffish likes of organized-crime bosses, venal cops, predatory robbers (known as ``swifts'' in the hot-rocks trade), acquisitive fences, and even a few semihonest merchants. With a little bit of luck, a full measure of street smarts, and timely if offbeat assistance from Maddie, Mitch (who worries some about being a kept man) eventually retrieves what he has been told is the loot. As it happens, the swag is said to have included some unreported items--a matched pair of large emeralds with religious as well as intrinsic value, for which the sinister agent of Tehran's vengeful theocracy is willing to pay $25 million. This intelligence sets Mitch off on a second investigation, but he's joined by a host of murderous fortune hunters also eager to collect the parlous Persian's reward. While clever Maddie (whose unsighted state may not have been caused by physical problems) eventually solves the green-ice mystery, the plot takes a couple of unexpected turns before reaching its plausibly happy end. Browne's flair for depicting professional theft, commercial ethics, high finance, low comedy, and the wages of the deadlier sins makes for an elegant, sexy lark of a novel.