Recording ICCS Certification Dates

So I brought some specimen coins into ICCS for re-holdering as the old holders were getting hard to see through, I spoke to the son, who's first reaction to them was something along the lines of "wow! These are really old!" He then proceeded to go get an old book off the shelf which appeared hand written, and looked up the certificate prefixes and listed them to me. It was quite interesting seeing him get so excited about old holders. He then re-holdered the coins for me and they look a million times better..before leaving I asked about a couple other cert prefixes I had remembered from my collection and was very interested in the answers I got! I'll list the coins and their certification dates later in the post. My reason for posting this is because I recall a thread about someone trying to document all the ICCS prefixes and attempting to catalogue them with the times they were used, so I'm posting this in the hopes someone rediscovers that thread or that the poster of that thread finds this one and finds my info as useful and interesting as I did!


1937 1¢, SP-65 "Mirror Type; Red", cert prefix: HE, Time of Grading: April 1992

1944 5¢, SP-64, cert prefix: AQ, Time of Grading: September 1994

1937 10¢, SP-66 "Matte Type", cert prefix: CF, Time of Grading: January 1991

1937 50¢, SP-66 "Mirror Type; Cameo", cert prefix: HE, Time of Grading: April 1992

1937 $1, SP-67 "Matte Type", cert prefix: CF, Time of Grading: January 1991

1966 $1, SP-67, cert prefix: SA, Time of Grading: June 1990- An important note about this coin and certification number, this coin is ultra heavy cameo and received no cameo designation, so I believe it may be from a time where they wouldn't give Specimens a cameo designation. Another note: I've seen 1949 dollars from this SA prefix in PL holders.