I found this statement online pertaining to early 1970's DCAM Proof coinage:
Quote:
Up until the mid-1970s, not all proof coins that were minted had a cameo contrast. The technology available to the mint at that time only allowed for first 30 to 50 proof coins produced from a new set of dies to possess the deep cameo contrast. As the dies continued to be used to produce proof coins, the frosted surfaces of the devices became more mirror-like with each proof coin struck.
So that's roughly 50 coins struck before they transitioned into full mirrored proof coins like some of the known examples of this unusual variety.
However ,I feel that ANY attempt at calculating a realistic survival estimate of this unusual variety would be virtually impossible (mathematically speaking), due to the
unknown variable of how many coins were found and removed from the bins by mint officials, immediately following the discovery and replacement of this blatantly obvious flawed reverse die.
Then you must consider, of the nickels that
were overlooked, how many were able to go undetected and become successfully hand placed into proof sets, heat sealed and then somehow able to pass through the rigid final visual QC inspection (looking for mintmark presence and proper coin alignment), before being sleeved, boxed and ultimately shipped out to dealers and customers alike.
Taking all those factors into consideration, I have come to the following conclusion...
Until this very unusual proof variety receives the proper recognition and attention from
"the powers that be", whom have the ability and resources to easily make this spectacular multi-variety proof coin known to the entire numismatic community, its actual population will most likely remain a mystery.