Cynthia's test impressions make technical sense, what might be expected just from material knowledge. : "The regular sterling will often go quite dark or even black while the AS will only yellow or brown at most." I believe your "testing" results are uncontrolled and results out of context in some fashion.
As I stated in an earlier post, the I gave was
incorrect. It had been some time since I had worked in anything other
than Argentium Sterling Silver (I love the alloy). I remembered doing
the test, nearly a year ago, with the results as I had posted. Later
I remembered that that particular test was with fine silver…apples
and oranges. The statement that “The regular sterling will often go
quite dark or even black while the AS will only yellow or brown at
most.” is correct. I apologize for giving incorrect
Marty Andersen