Petzite Sylvanite 1.786cts Trillion Cut Black Gemstone 8.59 X 6.36mm H2.5-3 Montana USA T339 Loose Faceted Gem Stone Rare Triangle Petzite Sylvanite 1.786Cts Trillion Cut Black Gemstone 8.59 X 6.36mm H2.5-3 Montana USA T339 Loose Faceted Gem Stone Rare Triangle