If the seller made an actual provable mistatement of fact (i.e. he lied in a provable way), you could sue him for fraud--IF you have you physical address (you can't sue without a physical address) and IF the cost and trouble of a lawsuit is economically worthwhile to you. But if he stated only that a watch was "inherited" but did not claim it to be a certain model or a certain age (e.g. an antique), then it's not clear he lied: you can "inherit" knock-offs and "fake" watches as well as truly valuable ones. Fraud would have to be a lie, not just something you may have misinterpreted; and since the only way to recover compensation in case of fraud is a lawsuit, it simply may not be worth pursuing or practical to pursue.