Chalmers Topaz
The Chalmer's Topaz is a topaz gem weighing 5,899.5-carats located in Chicago, Illinois' Grainger Hall of Gems, in the Field [Museum of Natural History]. It was named for former Field Museum trustee William J. Chalmers and his wife Joan Chalmers, who established a fund used to purchase gemstones for the Field Museum collections. The Chalmers Topaz is one of the largest cut topaz gems in the world.