One of the world’s oldest gems, December’s birthstone, turquoise, plays an important role in ancient and modern culture. Treasured by groups ranging from the Egyptians to the Native Americans, turquoise is thought to be a source of healing. Whether you’re interested in turquoise for its protective properties or simply its rich blue colour, there are plenty of beautiful pieces to marvel at in Sotheby’s jewels sales. Click ahead to see some of our favourites from our recent New York and London auctions. –Stephanie Sporn