HONG KONG – A white diamond the size of a small egg sold for $30.6 million dollars at a Hong Kong auction Monday night, edging out the previous record for such a stone set just six months ago.

Two phone bidders competed for the 118-carat rock from Africa in six minutes of measured bidding until one dropped out at the Sotheby’s jewelry auction, part of fall sales of art and collectibles by the firm and its rivals.

The twice-yearly ritual in this southern Chinese metropolis has made the city one of the world’s busiest auction hubs.

The “flawless” oval diamond, mined and cut two years ago, was hammered down for $27.3 million, just under the low end of the $28 million to $35 million estimate range set by Sotheby’s. Total price including commission came to $30.6 million.

That was more than the previous record of $26.7 million for a white diamond, set in May.