Egg-sized diamond sells for record-setting $30 million

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)

The oval white diamond that was auctioned Monday.

AP

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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