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This undated photo is provided by Sotheby's which they claim shows an invisible ink signature. Sotheby's says it has discovered that Jean-Michel Basquiat secretly signed one of his paintings in invisible ink. The auction house is selling "Orange Sports Figure," estimated to be worth between 3 million pounds and 4 million pounds ($4.7 million and $6.3 million). Basquiat, a grafitti artist who became a New York art star, signed relatively few of his canvases. But Sotheby's said ultraviolet light revealed the artist's name and the date 1982 beneath the layers of paint. (AP Photo/Sotheby's)

Hidden Basquiat signature found on work

Thirty years ago, artist Jean-Michel Basquiat secretly signed one of his paintings in invisible ink, says Sotheby's auction house, which discovered the hidden autograph as it was preparing the painting for sale.