Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Metallic
Uneven, Uneven, Gems, Sixth Edition (2006)
CuSMichael OâDonoghue , Gems, Sixth edition (2006) More from other references
Al 2O 3Michael OâDonoghue , Gems, Sixth Edition (2006)