Concert audiences may never know if a violinist is playing on a rare instrument from 18th-century Italy or a modern one that sells for the cost of a used sedan. But don't tell that to the owner of the "Lady Blunt," a 1721 Stradivarius violin that sold for $16 million at an auction last June. Or the recipient of a 1707 Stradivarius cello owned by the late Bernard Greenhouse that fetched $6 million in January.

Antique instruments are selling for astronomical prices these days, but some question whether they deserve all of the accolades. In a controversial study published last month in the Proceedings of the National Academy of Sciences, blindfolded experts were unable to pick two Stradivarius violins from modern instruments, based on their sound alone.