I bought a 1937 Australian Proof crown in 1975 for $1700. It was in a heat sealed PVC flip and authenticated by ANA Certification service with a Registration Number C2291 and small certificate. I just took it out of the bank safe deposit box and it has some PVC oil on it so I carefully cut the flip and removed the coin. I then carefully placed the coin in a beaker and poured acetone in the beaker. I carefully swished the acetone, not the coin, in the beaker. I then carefully removed the coin and let it air dry. I did this three times and it looks like two more treatments will totally remove the PVC oil. Has anyone else had this problem with the old ANA service using heat sealed PVC flips? How do I find out if the certificate registration number is authentic for this coin?