The turquoise was filled with a mixture of crushed pyrite and polymer. Photo by C.D. Mengason. The Carlsbad laboratory recently examined a 78.60 ct greenish blue oval bead with patches that contained ...

Lapis frequently contains varying amounts of whitish calcite matrix—the host rock that surrounds the gem—or flecks or veins of glinting yellow pyrite, or both. The gem can also have a smoothly uniform ...