At Gene's suggestion, I searched the entire TCR5 database for HHR chips attributed to the 1950's. I found none other than the D4C.
On the other hand, I was able to find 31 chips with the HHR rim attributed as early as 1964. If you'd like to check them yourself, look at:
Las Vegas: Riviera
Montgomery Pass: Montgomery Pass Lodge
Tonopah: Tonopah Club
Jackpot: Diamond Jim's
So what does this all mean? Only that, as with many other things in the hobby, we don't know for sure. Howard Herz's statement that the HHR mold was first made by Langworthy in 1970 could be wrong: it could have been made earlier by someone else, or the date could simply be too late.
On the other hand, it may mean that our estimates of the age of the chips listed above (and the D4C) are wrong.
As Gene and many of the rest of you know, having conducted your own original research, it's pretty common to hear conflicting stories. Memories are often faulty, and unfortunately we don't have authoritative records in most cases to fall back on. I know of at least three sources for the claim that the D4C HHR chip is legit: two dealers and Gene's source. And the date attributions above, although not perfect, were researched carefully as well. So was Howard's statement.
So where are we? Well, I think the value of the HHR D4C chip in TCR5 reflects the uncertainty surrounding the date of the chip. In fact, that's why we put the comment "mold seems late for chip" right in the book. I know I paid more for that chip several years ago than TCR indicates it's worth now.
It would be great to find a definitive answer, but I don't hold out much hope that we ever will!