Concerning Greg's post
"There are only Two exceptions I know of where real gold does not look like gold. One is Black Hills Gold, that comes from the Black Hills of South Dakota. Which is often less than 10K Pure but is still referred to as gold. (Don't ask me why)"
Black Hills Gold looks like any other yellow gold. Originally, the reason it was called Black Hills Gold is simply that it was mined in the Black Hills area of western South Dakota. The Black Hills were referred to as such because their higher elevation made the forests look black from the eastern plains. Out of the 1870's gold rush there came a style of jewelry featuring grapes and leaves, actually pink leaves and green leaves made by alloying copper and silver with 12K gold.
Modern Black Hills Gold
jewelry is made with regular gold, mostly 10K (with 12K leaves) because of its better wear charcteristics. But it looks just like any other gold, except for the alloyed 12K leaves. For jewelry to be called Black Hills Gold, it must be made in the Black Hills, but the gold needn't be mined there.
For a great description and excellent video of the jewelry-making process, visit Black Hills Gold Jewelry blog