UnevenWalter Schumann, Gemstones of the world (2001) More from other references, UnevenWalter Schumann, Gemstones of the world (2001) More from other references, Uneven
Gemstones (2009), UnevenArthur Thomas, Gemstones (2009), Brittle, Uneven
(Zn,Fe)SMichael OâDonoghue , Gems, Sixth Edition (2006) More from other references
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