Is a gold bullion bar that has a copper base worth anything or is it useless? Thanks!
Gold copper alloys are red in color, often referred to as Rose gold or Tumbaga gold. Usually silver and copper are used in equal parts to make yellow gold alloy. If alloyed with silver alone, the gold alloy will be green in appearance. White gold is gold alloyed with Nickel or palladium. Other colors such as blue and purple are possible with other metals but are brittle yet they are useful in inlaid jewelry. Black gold is based on an oxidation layer which is dependent on the base metal alloyed with and the coloration only exists at the surface. If the gold content is 99.9% then it's considered 24k gold though some countries will allow 99.0% gold to be called 24k gold. Gold is almost never available pure as it would be too soft. Most gold alloys will be gold, silver, copper and a little bit of zinc to harden the alloy, equal parts of silver and copper gives the alloy the appearance people expect of gold. The value of the bullion bar will be based on it's gold content. You should be able to determine it by measuring it's specific gravity. Weighing it in air and weighing it in water. Take it to a coin dealer if you want an authoritative opinion of it's value.
