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 IV 2015. "GemStone IV" is a text-based game built on Simutronics' proprietary engine, the IFE (Interactive Fiction Engine). This engine is capable of changing nearly any aspect of the game on the fly which allows updates without the necessity for downtime. Due to the use of the IFE, "GemStone" is rarely taken offline, giving a 24-hour uptime cycle aside from the occasional game crash. The "GemStone" interface is simply a text stream, and the game can be played with a Telnet interface after authentication. There are several official interfaces to the game, as well as several unofficial ones. The oldest interface