To know your accurate gold price, provide weights of gold in air and water to the 4th decimal place. The impurities will vary. Assume one of the predefined ratios based on your understanding. The ratio of copper to silver in your gold will not vastly change the purity calculation. If you do know it, however, it will increase precision.
To weigh your gold in air place it on a 5 digit scale; to weigh your gold in water place it in the submerged boat.
The impurity ratios for your region may be standard (ie Peru Alluvial, Indonesia Primary) in which case choose from the drop down menu. Or if you know the exact impurity ratio, simply populate the element inputs.
Although each predetermined ratio is named, chose the one that best represents your DORE. The names are simply easy ways to remember how to run the calculation.