Gemstone usually found in. For example, diamonds, which have a cubic crystal system, are often found as octahedrons. Gemstones are classified into different "groups", "species", and "varieties". For example, ruby is the red variety of the species corundum, while any other color of corundum is considered sapphire. Other examples are the emerald (green), aquamarine (blue), red beryl (red), goshenite (colorless), heliodor (yellow) and morganite (pink), which are all varieties of the mineral species beryl. Gems are characterized in terms of refractive index, dispersion, specific gravity, hardness, cleavage, fracture and luster. They may exhibit pleochroism or double refraction. They may have luminescence
Gemstone Publishing regarding Disney characters, and started publishing comic titles previously owned by Gemstone in the second half of 2009. Gemstone Publishing Gemstone Publishing is an American company that publishes comic book price guides. The company was formed by Diamond Comic Distributors President and Chief Executive Officer Steve Geppi in 1994 when he bought Overstreet. Gemstone published licensed Disney comic books from June 2003 until November 2008. The company has also reprinted EC Comics of the 1950s. BOOM! Kids acquired all comic publishing licenses regarding Disney characters in the second half of 2009. Gemstone's flagship publications were comic books featuring Disney characters;