Reuven sold Simon gold rings, and Simon sold them to Levy and they received monies from each other. Levy subsequently demanded to return the rings to Simon, claiming that the rings were joined with silver only, and not with a mixture of gold and silver as was the custom of old. Simon replied that this case was not one of erroneous transaction, since all rings made in our day are joined thus, of unalloyed silver only, and this is not a case of imitation… It is well known among Jews that rings made in our day, in keeping with the market vendors wishes, are joined with silver only, and a buyer buys according to current custom. The obvious and evident fact of the matter is that their sale price is at rates far below the rate for gold, and since this fact is simple and known throughout the city, what basis can there be to consider this an erroneous transaction, even if it is an imitation…?
We learn from this that the case of even a complete imitation, such as our case – made of gold but contains silver – when it customary to fashion imitations, is not termed an erroneous transaction. Even in the case of a complete defect, the customer must swear that he knew not of the defect or was reconciled to it. In such a case, the vendor reimburse the money he took, minus his profit from the transaction, as in the law for cattle and land.