(IDEX Online) - A flawless 101.38-carat diamond has become the most expensive gem ever sold in a cryptocurrency transaction.The pear-shaped D-color Type IIa diamond, named The Key 10138 after its carat weight, fetched $12.3m, to be paid in Bitcoin or Ethereum by an anonymous buyer.It failed to reach its $15m high estimate in a single-lot at Sotheby's Hong Kong on Friday, but came close to being the most expensive physical item ever sold for cryptocurrency.That record remains with the anonymous street artist Banksy, whose Love is in the Air painting sold in May for the crypto-equivalent of $12.9m. "By introducing this innovative payment option to our luxury sale, we open up new possibilities and expand our reach into a whole new clientele, many of whom are from the digitally savvy generation," said Wenhao Yu, deputy chairman of Sotheby's jewelry department in Asia.