FBI Is Probing Diamond Deals Struck by Founder of Jeweler Lugano

Federal authorities are investigating off balance-sheet transactions involving Lugano Diamonds & Jewelry, a chain of high-end boutiques that’s accused its founder of misrepresenting diamond investments he brokered with wealthy clients.

FBI agents have interviewed individuals who struck deals with Lugano founder and former chief executive officer Mordechai “Moti” Ferder as part of an investigation into the business, according to people familiar with the matter. A Lugano spokesman said the boutique is cooperating with the probe.

The Newport Beach, California-based chain of about a half-dozen shops, which is majority owned by Compass Diversified, sued Ferder in June and accused ...