Alexandrite is a rare variety of mineral that changes color depending on the light, according to the Geological Institute of America. Some even call it "emerald by day, ruby by night." The stone ...

Jewelry auctions are in full swing for the holiday, and, in the spirit of the season, red-toned stones topped the lots for both Sotheby's and Christie's. Rubies, spinels, and Alexandrites raked in ...