The Gemological Institute of America's world headquarters in Carlsbad, Calif., has installed a weighty new exhibit. "Giant Gemstones and Colossal Crystals" features one of the world's largest doubly terminated amethyst crystals, weighing in at 164 pounds, and one of the world's largest cut gemstones, a 500,000-ct. rutilated quartz. Among the other mammoths on display are a variety of large, well-formed rough crystals and faceted gems of quartz, topaz, and beryl, most of which weigh more than 100 cts. The exhibit, which includes information about the rarity, formation, and origin of big gem specimens, consists of pieces on loan from the Harvard Mineralogical Museum, several private collections, and GIA's own collection. For more information about this exhibit, as well as other offerings from GIA, call (800) 421-7250, or visit www.GIA.edu .