A 90% Dimes (BU) refers to a specific type of dime coin produced by the United States Mint. These dimes were minted before 1965 and contained 90% silver and 10% copper in their composition, making them highly sought after by coin collectors and investors due to their intrinsic silver content. The term "BU" stands for "Brilliant Uncirculated," indicating that these dimes were never circulated and have maintained their original mint luster and condition, further enhancing their value in the numismatic market.
