Bob,
I have a retail manufacturing jewelry store and buy 7 figures a year in gold. I also manufacture platinum & palladium jewelry so I have a little experience with PGM. I use two methods to determine the fineness of gold both in buying and selling. I have an Alpha Mirage S.G. scale that is fairly accurate in payouts on solid objects and I have my fourth XRF machine. By fourth, I mine I have upgraded to a medium grade SSD machine that I find to very accurate. By accurate, I mean I am being paid within $10-$20 on over $10,000 of what I call it. I have had my preferred refiner send three of their bigger customer's to show them how to figure payouts.
One of the bigger problems is figuring out what the true gold content of a bar of melted gold is soldification. Even when you melt and remelt the same bar in an Induction Melter, stir the heck out of it, and try all the different methods of cooling it, it's not the same mixture thru the whole bar. In the cooling process, the metals move around and you have to find a method to average out the readings. In the tight margins of payouts of refiners, the 1-2% margin becomes critical. Depending on your volume of business, the ability to determine the purity of your gold is critical. Unfortunately, it also requires an expense on your part either in purchasing the equipment or finding someone who will assay your metal.
We all have been there.
Good Luck,
Dan
