Psilomelane Cabochon, 13.20 cts.

This material typically exhibits swirls and alternating layers of black Romanèchite and gray Pyrolusite, both of which are a type of hydrous manganese oxide and can achieve a submetallic lustre (almost mirror finish).  This stone appears to be mostly Pyrolusite and has a subtle botryoidal formation pattern when examined closely.  Flat, semi-polished back with a beveled edge for ease of setting.  You will receive the exact gemstone shown in photos.

Weight: 13.20 carats
Length: 17.37 mm
Width: 12.18 mm
Height: 4.32 mm

Group: Hydrous Manganese Oxide
-Species: Romanèchite-Pyrolusite
--Variety: -
Trade Name(s): Psilomelane, Black Hematite*
Origin: Australia
Enhancement(s): (N) Natural

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* Using the term "black hematite" to describe Psilomelane is deceptive and a punishable crime under US Federal Trade Commission regulations. Hematite is an Iron oxide with a different chemical makeup.
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American Gem Trade Association Gemstone Enhancement Codes

Enhancement: Any treatment process other than cutting and polishing that improves the appearance (color/clarity/phenomena), durability, or availability of a gemstone.

(N) Natural
No modification; natural stones which are not currently known to be enhanced (or currently has no known modification process).