Jewel collectors, fearing that their eyes will be deceived by a counterfeit, will not buy a diamond unless the dealer guarantees that it is genuine. But why should a counterfeit give any less aesthetic pleasure when the naked eye cannot distinguish it from a real diamond? Both jewels should be deemed of equal value.
The principle that the value of a jewel should derive solely from the aesthetic pleasure it provides, if valid, most helps to justify the reasoning in the argument above.