HI, Here is what I would always do, If the person that is selling that 100 year old idem is on the up..up, then when you ask the person or seller to give you prof of how old it is, they will be glad to. You just ask the seller everything you can about the sale you are about to make. Remember you are the buyer and you have the right to know everything there is to know about what you are about to buy. If they are on the up..up you will know it, if not you will know that too lol. P.S Tell the seller that you did see this idem on amazon and see how they reacted. This gos for everyone here on ETSY get to know the people you are dealing with!