A diamond necklace with an illustrious, if mysterious, past sold at Sotheby’s Geneva yesterday for $4.7 million, outstripping its top estimate of $3.8 million, or 2.2 million Swiss francs.

The auction house said the necklace, composed of three rows of diamonds finished with a diamond tassel at each end, had emerged "miraculously intact" from a private Asian collection to make its ...