Two spectacular emeralds, among the world's largest and most unusual, are being displayed at the Smithsonian's National Museum of Natural History in Washington until Dec. 27.
The first, an enormous uncut, unpolished 665.4-carat crystal, was found in a Colombian mine in 1981. (The famous Hope Diamond, on display nearby, is only 45.52 carats.) The six-sided deep-green gem, which seems to glow, is rare because most large crystals are cut into smaller gemstones.
"The Mogul" emerald (shown here) is a historical as well as a geological treasure. It was carved in the 17th century for a Mogul prince and was probably sewn onto clothing. The emerald is carved with an Islamic prayer on one side and a floral design on the other.
Both emeralds have been lent by Allan Caplan, a private collector and gem dealer in New York. Information about the emeralds and the new Hall of Geology, Gems & Minerals - which will open in 1996 - can be accessed on the Smith- sonian's home page on the World Wide Web: http://www.si.edu.