Amen Dave!! Well put.
I think we need to make a thread called "Let's not get scammed, and how to avoid getting sheared".
Problem is, most of us small timers don't have the time or resources to fork over for an independent ICP, XRF, or AA analysis for the small lots we deal with on a regular basis.
Case example, I sent in about an ounce of what I knew to be pure 99.99% pure Pt (I had ran my own analytical tests) to Midwest Refineries only to be told some hogwash about how they'll XRF it and figure out if it's platinum, and how pure it is to +/-3% (they're really more accurate than that, generally +/- 1% but it can be better depending who's using it and how). Of course they'll take the value the machine gives and correct DOWN by 3%
In my case, since I sent in less than 3 troy ounces, they decided that they would settle for 95% of spot price multiplied by their 89% payout. I never knew I had to send in more than 3 troy ounces to be eligible for the 89% payout. To top it off, they told me it wasn't pure, when I knew it was. Anyway, by the time they were all said and done with their shenanigans, their 89% payout for "any amount" was down to 79% of spot price. Geez guys, at least put some fine print on your website!!
Oh, and when I called to ask why I was 100 bucks short, I got the "well, some of the metal vaporized when it was melted" which is a steaming shovel full of poo. I played along. I had half a mind to tell him that it's not my fault they don't know how to melt platinum, and more than half a mind to ask them how in the world they can make a noticeable amount of platinum volatilize at its casting point. The probably melted it in an induction furnace (which I assume they could afford, if they even have an XRF like they claim)...so unless they *grossly* overheated it, loss due to evaporation should have been nil.
Conclusion: Never, ever believe the "some of it evaporated" line. It's utter crap when applied to platinum, which is used in lab equipment up to its melting point because it doesn't gain or lose weight!!! It's not really that true for gold, palladium, or silver either. You can look up their vapour pressures yourself!
Conclusion: Their assay is probably biased.
I'm no where near an expert on refining, but I do have a wee bit of what I consider practical experience with the machines used for analysis, and just a little bit of chemistry under my belt. So being treated like a complete idiot was not only insulting, but rather amusing. They didn't fool me, and I'll not allow them to try ever again.