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 then to Gemstone, which has been the home of Cochran's EC reprints for over 15 years. Reprinting the Cochran/Gladstone-reprints of "The Haunt of Fear", "The Vault of Horror" and "Weird Science" (all 1992), Gemstone also republished (in single issue and 'annual' - four issues per 'annual' - format): Oversize, hardback, slip-cased collections of these comics had been previously published in black & white by Cochran during the 1980s as "The Complete EC Library". This Library was then added to by Cochran/Gemstone with 2005's "Picto-Fiction" collection, comprising the EC comics: "Confessions Illustrated", "Crime Illustrated", "Shock Illustrated" and "Terror Illustrated", along with