How is bullion purity determined?

Bullion coins are primarily valued for their precious metal content, weight, and purity, while collector’s coins (or numismatic coins) are valued based on rarity, historical significance, condition, and artistic merit. While both contain precious metals, bullion coins are typically bought as an investment, and collector’s coins are often sought after by hobbyists and collectors. The price of bullion coins is closely tied to the market value of the metal, while collector’s coins might be priced according to various factors beyond the intrinsic metal value.