Sotheby's has said it will accept cryptocurrency as payment for a rare diamond which is expected to fetch more than £10m.

It will be the first time that such a valuable stone will be available to purchase using cryptocurrency, the broker said.

Traditional money will still be accepted but the buyer of the 101.38-carat pear-shaped diamond will also be able to use cryptocurrencies Ether or Bitcoin.

The diamond, known as The Key 10138, is among just 10 diamonds of more than 100 carats to come to auction.

It will be offered in a single-lot live sale in Hong Kong on 9 July, with an estimated sale price of between $10m and $15m (£7.1m to £10.7m)

Yu Wenhao, deputy chairman of Sotheby's Jewellery in Asia, said: "This is a truly symbolic moment.

"The most ancient and emblematic denominator of value can now, for the first time, be purchased using humanity's newest universal currency.

"Never was there a better moment to bring a world-class diamond such as this to the market."

The diamond belongs to Type IIa, a rare subgroup comprising less than 2% of all gem diamonds, Sotheby's said.

Perhaps the most famous pear-shaped diamond is the Cullinan I, which is kept in the Tower of London and mounted in the Imperial Sceptre.