Five 17th and 18th century Rhino horn cups that the Antiques Roadshow have estimated to be worth a combined $1.5m are coming to auction at Sotheby's New York on March 20th.
The Ming and Qing dynasty cups form a key part of the auction house's Fine Chinese Ceramics & Works of Art sale.
Current owner Douglas Huber bought the cups for a combined $5,000 over a 40 year period. Antiques Roadshow expert Lark Mason valued them at between $1m-1.5m at a show in Oklahoma last year.
The pick of the bunch is an "Eight Immortals" specimen estimated at between $180,000 and $250,000.
"They are in superb condition and represent a fine and comprehensive group that showcases the different styles of these extraordinary objects," commented Sotheby's.
Huber told his local Tulsa World newspaper: "I have kind of been following prices of rhinoceros horn cups and they kind of skyrocketed."
Indeed they have. A carved Chinese libation cup from the same period sold for $340,000 at a US auction in May 2011, suggesting the upper end of Mason's estimate could well be broken on Tuesday.
Since 1976, trading of rhino horns has been illegal. "New" rhino horns are forbidden at auction, but confirmed antiques are an acceptable consignment.
Last month a £50,000-estimated Rhino head due for sale at a UK auctioneer was stolen. This is an increasingly common occurrence, as rhino horns are in much demand in the Far East, due to their perceived healing properties when ground down to form a powder.