Unless you are dealing in the Silver Strike Centers that aren't marked the information really has no bearing on selling the .999 marked centers since any dealer or refiner will treat them as .999 fine silver and buy them as same. Also there are dealers who will buy unmarked silver but the price is a lot less than marked silver.
One other thing of interest a few years ago I had a bunch of mixed silver refined and assayed by two different assayers and they both came up with a differnt purity, neither were that much apart and didn't make a difference in the buy price.
Walt