Number four in the Marshal Guarnaccia series in which the Sicilian inspector digs into the story behind a richly bejeweled body found in the Arno. It's a atmospheric tale involving not only murder but also blackmail, jewel theft, and drug dealing. The Columbo of Italy, Nabb's likeable Guarnaccia is not entirely at ease, a Sicilian living in Florence, but he's deceptively clever (and a solid citizen).  (ITL637, $11.00)