There are several qualities of mint. The latter is determined when designing each coin. This is not to be confused with the condition of a coin, which varies over time. Here's our classification of mint qualities:
Proof : this type of striking is distinguished by a "mirror-like" bottom and a usually "matt" relief. It is in fact the highest level of quality of striking and the price of this type of coins is significantly higher. Depending on the country, this level of quality has various names: Belle Úpreuve(BE), Proof (PRF or P), Polierte Platte (PP) or Flan Bruni (FB).
UNC / BU : There is a certain amount of intermediate type of quality used for collector or investment coins, for example for coins that have not been circulated (UNC), or are not intended to be put into circulation (BU). We group all these typing types under the name UNC / BU.
Legal tender : on quote.gold, we chose not to classify legal tenders for now.