I saw and pictured a coin today of an Israel 25 Prutah in a PCGS slab. It is a proof coin and I relized that if I saw this coin raw, I don't think I could identify it as a proof. What makes this proof?
There are several different type of proof coins. Several sounds like to few, but many sounds like to much. Many for the world spectrum. There are many different types of proof coins. (and proof-like). I don't think all are equal and there is no blanket answer to that question. Determination can prove to be difficult for some/most folks. Its the reason other folks write book about coins. And why TPG's are needed. There is an answer to your question, but I don't know what it is apart from "it says so on the slab".
