An upright piano used in 1942 film Casablanca has sold for $602,500 at a Sotheby's New York auction, to actor Leonardo DiCaprio.

In doing so it has shown a return of 5.9% pa on the $154,000 it achieved when selling to the consignor in 1988.

The other piano used in the film resides at the Warner Bros Studio in California

The impressive appreciation highlights the potential returns to be found at the top end of the movie memorabilia market - last year we saw Marilyn Monroe's "subway dress" from The Seven Year Itch sell for $5.6m at auction, providing a 27% pa rise in value over 40 years.

It is one of two identical pianos used in the film. The other is based at the Warner Bros Studio in California.

DiCaprio and billionaire Stewart Rahr went halves on the piano on December 14, reports the New York Daily News, and now plan to donate it to the Los Angeles County Museum of Art.

The piano's appeal stems from its central role in the iconic film, with Dooley Wilson's playing of As Time Goes By an enduring feature during Humphrey Bogart and Ingrid Bergman's love affair.

As Time Goes By is now synonymous with Casablanca, yet it was originally written by Herman Hupfield in 1931 for the play Everybody's Welcome.

The piano also engendered two of the film's most famous lines: "Play it, Sam", and "Here's lookin' at you, kid".

Sotheby's David Redden remarked prior to the sale: "How can anything say 'I love you' better than the piano from Casablanca?"

Paul Fraser Collectibles is currently offering a pair of Humphrey Bogart worn jodhpurs, which he sported as Don Ellis in the play Chrysalis in 1932.