‘The Enigma’: Mystery black diamond up for auction; c
A black diamond weighing a staggering 555.55 carats is going up for auction at Sotheby’s and living up to its name “The Enigma.” Bidding opens on Feb. 3 at 6 a.m. PST (1400 GMT) and closes on Feb. 9, Sotheby’s said, adding cryptocurrency will be accepted for payment of the diamond. Sotheby’s said it is…