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 Suspenstories" Vol. 1 and "Tales From the Crypt" Vol. 1 have been published. In early 2009, the future of Gemstone Publishing was unclear, after reports of unpaid printing bills, particularly from the EC Archives. In April, Geppi responded to the uncertainty, noting that while there had been "a reduction in staff at Gemstone," such moves did "not [signal] the end of Gemstone Publishing." Seven months after Geppi's optimistic statements, the last batch of Gemstone's Disney comics appeared in November 2008, complete with previews for next month's issues that Gemstone was to fail publishing. BOOM! Kids acquired all comic publishing licenses