A- the world's 403rd richest person, according to Forbes - has sold for $7.7 million at a Christies Auction.
Annenberg - who died in March, aged 91 - was US Chief of Protocol in the Reagan administration, and the widow of Walter Annenberg, a billionaire publisher who became US Ambassador to Britain.
She was famed for her glamorous life, philanthropy - including setting up the Annenberg Foundation - and her fine taste in jewellery.
The so-called Annenberg diamond ring was bought for her 90th birthday.
Ms Annenberg would have reportedly been proud of the 32.01 carat diamond's sale, which easily surpassed experts' pre-auction estimates of $3-5m.
The emerald-cut, pure diamond ring is roughly the size of a walnut, and was toured around various places including Geneva, London, Hong Kong and Los Angeles to find a suitable buyer.
It was sold to an unnamed telephone bidder.