Here is something that makes all goldsmiths swoon... an ounce of pure gold. I will use it by alloying it into probably 18 karat gold (my favourite) to make bezels and maybe some casting. Gold is such a treat to work with and many people don't realize that this is what you start with to create all your gold alloys (12k, 14k, 18k, etc.) even white and rose gold! It just depends on what metals you mix it with and how much of this alloy you use.
For more depth on the subject, check this out: