Yeah, you're not wrong about it being pretty difficult to prove authenticity, and given the item I understand being cautious.
When I won the competition they gave me the option of either a Sony entertainment system or the coins. I think they thought I would pick the system as it took them a few months to design and mint the coins. They even ended up hand delivering them to me, however they didn't provide any sort of physical documentation.
I will talk to a local jeweler and see if it's possible to have them verified.
I also have photos they provided me while the coins were being minted which are pretty interesting, I'll find those and post them up.
I can also provide screenshots of the emails I received to help verify the coin.
If anyone has any other ideas of things I can do to verify that'd be much appreciated
