GENEVA (AP) — Sotheby's is putting up for sale a fancy vivid, pearl-shaped pink diamond said to be the largest of its kind sold at auction and expected to fetch a price between $28 million-$38 million.

The 15.38-carat "Unique Pink," mounted on a ring and touted for its clarity and pure structure, is the star lot in the Geneva auction taking place Tuesday. The diamond was mined in South Africa.

The current record for the sale of a pink diamond was $46.2 million, set five years ago by the "Graff Pink."

The record sale for any diamond was $48.5 million of the 12.03-carat polished "Blue Moon" diamond earlier this year. Hong Kong billionaire Joseph Lau bought it as a gift for his 7-year-old daughter and had it renamed "The Blue Moon of Josephine."