Todd M. writes: I have an MS-60 1900 Gold $5 coin and I have a new 1998 $50 Gold Eagle. My question is this: How come my 1900 $5 gold piece is dull? How come it doesn’t shine like the new gold coin? Gold doesn’t react to tarnish! My 1900 piece looks almost orange! Any explanation? Thanks, Todd
The Gold eagle alloy is 91.67% gold, 3% silver and 5.33% copper giving this coin almost a white-gold appearance. The 1900 Liberty half eagle is 90% gold and 10% copper giving this coin an red orange-gold appearance. Pure gold is too soft to be used in pure form but adding a small amount of other metal such as copper, increases the hardness tremendously (That is why gold crowns on teeth can withstand chewing). As you can see, the shade of color of gold coins depends on the alloy used.
The “luster factor” is dependent on how much pressure is applied to the flan (blank) when it is struck by the dies in a coin press. The harder the pressure the more the metal will flow creating the microscopic, radial lines that are responsible for mint luster. Softly struck coins exhibit soft mint luster and may have weaknesses in the design. Excessive pressure will create a coin with lots of luster and a sharp impression but will reduce the life of the die. Another killer of mint luster is cleaning. Even a small amount of cleaning can remove some of the flow lines, making a coin look dull.