Bill - The test we use, primarily when testing items for appraisals or
before repairs is to take a very finite sliver of the white metal and do a
melt test. This is what the german metal assayers taught me. Use a flat
graver and take the sample from a discrete location, like the
underside/azured areas, where the small scrape will not be discerned. This
eliminates the need to perform an unsightly or dangerous test like filing
or god-forbid a heat test. Then simply melt the sample on a charcoal
block. There’s no questioning how easily gold melts in comparison to
platinium, which would require considerably greater heat and visiual
protection to accomplish.
My motto: White gold is yellow gold that’s been given a sex-change.