Collector gamstone: Cuprite - 24.49 ct. Emke Mine, Onganga (Onganja), Seeis, Windhoek District, Khomas Region, Namibia.  photo Heritage Auctions

Cuprite is a minor ore of copper, known for its distinctive red color - hence its nickname Ruby Copper. Mostly known to mineral collectors, it wasn't until the Namibian discovery in the 1970s that material large and transparent enough to facet, transformed this mineral into a rare gemstone. Virtually all of the gem Cuprite in the world has come from this singular deposit at Onganga - and no more gem grade material has been found anywhere since. This rare collector gemstone has deep ruby red coloration with an adamantine, almost metallic luster. It was facetted by Spectrum Award winner Mark Kaufman. A sizable oval gem, it measures 19.7 x 14.3 mm, weighs 24.49 carats, and is in excellent condition. Estimate: $1,800 - $2,200.

Heritage Auctions. 2012 May 20 Natural History Signature Auction- New York