The only known issue (which is pretty much a non-issue, just an inconvenience) thus far has to do with the font I used to print the private key inserts. It is sometimes challenging to distinguish which character the private key is due to similarities in the font and the small font size. If you are having trouble redeeming a private key and you are sure you are doing it correctly, then try looking for characters that may look alike, such as: 8 and B, k and K, or 1 and I.
In one instance, someone was having trouble redeeming a CryptoVest coin, and after giving the usual directions of how to redeem them and it still not working, I then asked them to send me a picture of the coin insert. After a lot of trial and error switching out lowercase characters for uppercase etc, I finally figured out that the lower case k looked like an uppercase K. After switching it out I was able to redeem the value, which I forwarded on to the coin's owner (+ a Litecoin for bringing it to my attention).
As of today this remains to be the only known issue that I've identified regarding the coins that I made, and it's an easy fix.
I've had absolutely zero notifications of anyone having their private keys compromised, of any counterfeit coins, or any other major issues. I hope and pray that this will continue to remain true for eternity, but please feel free to come forward (publicly or privately) if anything happens to your keys, or if you see anything suspicious. I would like to be alerted, and to alert the community. Thanks!
Can I still purchase these coins without a hologram? I want to buy them if there are any left. Are they pure silver coins?