As for the 3M tape, it's not evidence that the stone has been replaced necessarily. however the chips left from the original stone being removed not matching the chips in the stone that is presently in the box is.
As for the PayPal issues. I believe discussing in more detail would likely not be within forum rules. Suffice to say that I was unaware that merely communicating through that service would have any impact other than you receiving a message from me. And for that I apologize.
As stated before, I believe you are an honest man with good stones for sale. This is merely an unfortunate occurrence and that is the risk we take buying and selling vintage natural stones