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Howardite aka Rattlesnake Jasper designer gem 5/2/2018 01 - 35 x 19 x 3.5 mm - 16 carats - This unusual cab is cut from one of the most rare and sought after semi-precious stones in the world. The material is said to be an agatized/silicified/opalized tuff of which the location of the deposit is apparently lost or mined out, nobody seems to know exactly. It has been thought to come from northern Nevada. John Sinkankas mentioned in the book "Gemstones of North America" (1959) that this material was more like chert and that it came from California (shown in a photo with other California agates). Regardless of locality it is some of the rarest lapidary materials available. This unique designer teardrop gem has a beautiful low dome, girdled sides and a flat beveled back with glossy luster. There are some druzy surface voids that do not detract from the quality or beauty of the stone. This is a rare and very nice cabochon of this illusive stone. Here is a video clip to see the stone in motion: