CA And DC Half Dollar Designs...

Ah...LOL...the "CA" actually means "cameo" and the "DC" means "deep cameo", which pertains to the criteria PCGS uses to distinguish proof strikes.

In regards to the SMS coins, the vast majority of them are neither CA or DC since they are not actual proof strikes. I do not think there is any hard and fast measurement to differentiate between CA and DC but if you look at them side by side, the difference in the cameo frost is apparent. I believe that it is more of a subjective measurement. Any recently minted proof coins will be DC since they are minted to be that way but that was not always the case. Formerly, a DC would be produced with the first few strikes of a die, then some CAs, and the rest of the die life would produce brilliant proofs with no discernable frost.

OneMoreRoll,

Cameo and Deep Cameo are normally associated with "Proof" strikes and not business strikes. The Special Mint Sets (SMS) were special strikes over business strikes when Proofs were not offered in 1965-67.

Cameo refers to the level of contrast between the fields and the devices (lettering, numbering and images). If there is very little contrast between them, then the coin will not earn a Cameo designation. If you notice a definite contrast, you have a Cameo. For the coin to earn a Cameo designation, it has to display this contrast on both sides, i.e., if the obverse has contrast, but the reverse does not, then it is not Cameo.

Deep Cameo is defined as a stark contrast between fields and devices. You can see this in photos where the fields are black and the devices are pure white. It is caused by burnishing of the devices (rough polish) by the mint. This will create a frosted surface that reflects light in all directions. The fields being mirror smooth will only bounce light in one direction. So, if you hold the coin just right, the fields are black and the devices are white. This frosting doesn't last that long in the minting process and the devices on the dies wear smooth like the fields. Very few coins from a set of dies will earn DCam designation.

Hope that helps.