Diamond prices keep breaking records.
The latest is a 118-carat, flawless D-diamond that was auctioned off by Sotheby's on Monday for $30.6 million. That beat the previous auction-price record for a white diamond of $26.74 million, paid for the "Winston Legacy" this spring at Christie's.
The 118-carat diamond, about the size of an egg, sold for the low end of its price estimate of $28 million to $38 million. Sotheby's declined to comment on the buyer or the buyer's nationality.
(Read more: Investing in diamonds? Good luck getting prices )
Large, collectible diamonds have seen big prices recently as the super rich from emerging markets turn to large jewels as portable stores of wealth.
Mahyar Makhzani, the London- and Geneva-based managing director of the Sciens Colored Diamond Fund, estimated that more than 80 percent of large-diamond sales over the past three years have gone to Asian buyers.
(Read more: Sotheby's sells 74 carat diamond for $14 million )
The 118-carat stone was discovered in 2011 in the deep mines of South Africa and was 299 carats before it was cut.
-By CNBC's Robert Frank. Follow him on Twitter: @robtfrank .
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