I’ve been using an off the shelf testing kit for gold: three acids
10K, 14K and 18K, 3 needles of yellow gold 10-18K, and a touchstone.
These have proved useful for testing unknown yellow gold for trade
from customers and seems to indicate properly. However, if I draw a
strips of 10K white gold, the 10K test needle, and sterling, either
the old fashioned copper alloyed or Argentium, these lines test
positive too and do not dissolve with the 10K acid.
I need to be able to test 10K and 14K white without ambiguity,
particularly against sterling silver. There is a lot of Rhodium
plated sterling that looks like white gold, and it is impossible for
me to tell visually by eye when the Rhodium is filed off if it is
silver or gold. How do I do this (other than by guessing density)?
Any thoughts would be appreciated.