Yttrium aluminium garnet (Ce:YAG) is used as a phosphor in cathode ray tubes and white light-emitting diodes, and as a scintillator. YAG for a period was used in jewelry as a diamond and other gemstone simulant. Colored variants and their doping elements include: green (chromium), blue (cobalt), red (manganese), yellow (titanium), purple (neodymium), pink, and orange. As faceted gems they are valued (as synthetics) for their clarity, durability, high refractive index and dispersion. The critical angle of YAG is 33 degrees. YAG cuts like natural garnet, with polishing being performed with alumina or diamond (50,000 or 100,000 grit) on common polishing laps. YAG
GemStone IV all players to begin anew. "GemStone III" evolved into "GemStone IV" in November 2003, but the game world and character records were maintained over the transition. "GemStone III" was promoted on GEnie by promising players the opportunity to receive real-life versions of gems found in-game, something that persisted for many years. "GemStone" originally operated with a license to use the Rolemaster game mechanics and Shadow World environment from Iron Crown Enterprises (ICE). In 1995, Simutronics and ICE agreed to let the business relationship expire, necessitating the removal of all ICE intellectual property from "GemStone". Many of the game changes were