As an early Casascius buyer/holder I viewed these coins as nice memorabilia items and didnt think of getting Chain of custody for future authentication.
Obviously with the high value these coins have now it's becoming something both seller and buyer want assurance on.
So if a seller doesnt have chain of custody would the next best solution be to have the coins in question checked by trusted experts? Eg: Hologram, coin pressing, ink used etc.
Suggestions for other methods to authenticate?
Post some photos here with the public key blurred if need be. We can take a look at the coin and hologram and let you know.
Also read this thread.
https://bitcointalk.org/index.php?topic=3257048.0