Lately a number of jewellers' "925" silver marking punches/stamps have been sold via ebay. While it is perfectly legal to sell such stamps, it is highly illegal to stamp items that are less than 92.5 parts per hundred silver with such markings. Unscrupulous sellers may mark items with a minimal (or none at all) silver content with these stamps. Be on your guard when buying such items as jewellery, trinkets and military badges, and if you have the slightest suspicion ask the seller to give you a written guarantee and to accept the return of questionable items. Any reputable seller will agree to this.
If you believe you have been defrauded report the matter to ebay and to the police.