I have no way to verify this, but I have a theory on the 1964 Accented Hair variety Kennedy Half dollars. I recently purchased five (supposedly) sealed 1964 Proof sets. Three of them were opened, but of the open ones, two had Accented Hair Kennedy coins in them. Now, for the theory. The two envelopes that contained the Accented Hair Kennedy coins had a bolder typeface on the wording. (This comment applies to all the wording, including the "1964 P.C." part.) The third opened envelope had a regular 1964. As I said, I can't definitively test the theory, since the two unopened envelopes are both of the "non-bold" typeface variety. So, if anyone has a bold and non-bold type face unopened envelope, and they are willing to take the risk, it may behoove you to open the bold one, if you are still trying to get an accented hair to finish your set. My camera battery just died, but I'll post pics of the two accented hairs using my junkie phone camera and junkie magnifying device.
Here are the pictures. Sorry about the second I being super blurry. I basically was taking the picture with a magnifier over the camera phone lens.
One way to test this theory is see if the Mint used the bold face printing early and then changed it later on. The Accented Hair varieties was made early in the production of proofs.
Only problem is that reproduction enveloped have been on the market for years. Yes they fake the envelopes on those so nothing is for sure.
That's true. Many of the so called sealed envelopes,"never opened", are reproduced envelopes, or at most, resealed envelopes that have been examined previously.
Oh well. So much for my theory, then. But, to the question of the early release envelopes being bolder print, that could be possible... Maybe the Mint was trying to save money on ink.
If people have what they believe to be sets in their original envelopes and a significantly higher percentage of the bold envelopes are AH's, that could still mean something.
I suppose that's true. I mean, it's more of an "elimination" type of theory. If anything, if it's true, it would mean that the non-bold envelopes won't hold the accented hair varieties. But, as others have noted, the envelopes have been redone through the years, so there's no way to really know.