A blue-and-white bowl purchased for $35 by an eagle-eyed antiques enthusiast at a yard sale has turned out to be an extremely rare 15th-century Chinese artifact that is expected to sell for up to $500,000 at auction.

The unidentified seller discovered the small floral bowl in a New Haven, Conn., yard sale last year and emailed images to Sotheby's for an evaluation.

Experts determined that the porcelain piece is a rare "lotus bowl" from the court of the Yongle Emperor, who ruled from 1403 until 1424, and it is one of only six such bowls known to still exist, according to Sotheby's. Inticate motifs of lotus, peony, chrysanthemum and pomegranate blossoms are featured on the Ming dynasty piece.

The six-inch bowl is estimated to bring $300,000 to $500,000 at a Sotheby's sale on March 17. Asia Week sales begin March 11.