Is Navajo jewelry stamped with the hallmark LMB Sterling mass produced and/or fake? I read somewhere to beware of that mark. I just bought a squash blossom necklace and it has these initials... did I buy a fake?

Larry Moses Begay signs his items LMB Sterling. Your item marked LMB Sterling is not fake. It was made by Larry Moses Begay. There was a point in time, during the early 2000s when the Begay family made a lot of jewelry, including squash blossom necklaces, in large quantities, but they are not mass-produced-on-assembly-line fabrications. They are handmade works of art in which each stone is hand cut and polished, hand set, etc.