A lot of newer proof coins are cameo, I understand they are because the dies are acid treated. But what causes an older coin to be cameo or deep cameo? If a proof coin is struck several times, I take it a cameo coin is struck even more?
The cameo effect is the result of a deliberate effort by the mint to make the coins look that way. Yes, they used to use acid to treat the dies, but that was many years ago. Since then they have used various forms of sandblasting, and today they use lasers to treat the dies. To produce the cameo effect the devices (basically all recessed areas) on the die are given a pebble effect, while the fields (all raised areas of the die) are polished. These two things are what produce the cameo effect. In today's world only the Proof coins are produced with cameo. But there was a time when most coins produced for circulation had the came effect also. The ones people are most familiar with are Morgan dollars. But halves, quarters, dimes, and all of the gold denominations of the period, were produced with cameo as well. But the mint did not take pains to make sure that every coin produced had the cameo effect. Only the coins struck with new, or fresh dies had cameo. And once the pebble effect on the dies wore out they went right on striking coins with those dies. So the result was that only a few of the coins struck for circulation had cameo. Morgans were an exception, not all, but a great many of the Morgans produced had the cameo. By the early 1900's the mint discontinued this practice and it was not until the Proofs of the '30s that cameo was again produced on coins, and then only on Proofs. And not all Proofs either, but only those struck with new and fresh dies. This practice continued until 1973 when the mint decided that all Proofs would have the cameo effect. That practice continues even today.
For Modern Proofs, the dies are "laser etched" via CNC which can produce some dramatic results if the die and the CNC program aren't lined up exactly.
the cameo on modern proofs the last couple of years looks terrible, very grainy and seem to lack any smoothness at all.
I need to respond to the OP's question. "What Causes Cameo?" The how's have been presented but not a specific answer. Answer: Cameo is caused by the use of contrasting metal finishes. Whether it's laser etched, sandblasted, or acid etched, the net result is contrasting finishes. Devices with an unever reflective surface definitely contrast with mirrored fields.
So how were cameo and deep cameo coins created back in the 1800's? Sandblasting and laser etching did not exist.
Micro Droids. I keed I keed! I suppose an acid dip could have been used, as previously described, followed by polishing of the fields.
Sandblasting did exist in the 1800's, can't give you an exact date but it existed. But I believe acid is what was used in the early years.
