Thank you, Andy. I tried the test again, using lightly sanded flat
sizing wire of pt, pd, 18kw and 14kw. Just when I was ready to give
up on changes, the iodine did, indeed turn clear on the pt. It just
took several minutes.
The pd stained black and reddish. Both golds reacted the same-- they
turned what I would call yellow-gray, and dull (the others stayed
Just then, our senior goldsmith came by and looked at my efforts. He
fetched the 18K testing acid and put a drop on each of the samples.
The pt did nothing (remained clear); the pd drop turned distinctly
yellow in a matter of 10 seconds or less; the golds stained
So now I feel equipped to distinguish decisively among the white
metals-- as long as they’re not some weird alloy.
I will add, for others new to all this, like me-- the red-brown
stain on the gold did not sand out nearly as easily as the other
marks, so I would avoid doing this. After all, you can ID the golds
using the acid and the rubbing stone.