The Mogok Ruby

Photo by Tino Hammid

Known variously as the Alan Caplan Ruby or the Mogok Ruby, this 15.97-carat untreated Burmese stone was sold by Sotheby's of New York in October 18th, 1988 for $3,630,000; a whopping $227,301 per carat. It was purchased by Graff of London, who reportedly sold it to the Sultan of Brunei as an engagement ring for one of his wives.