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Yellow rhodium, fake advertising?


#1

I recently came across an ad containing a of a piece of stainless
steel jewelry with a stone bezel set in 'yellow rhodium". I have
never seen such a claim previously. I know there has been quite a bit
of work on alloys of gold including rhodium and there are many phase
diagrams that show the results of gold/rhodium alloys. None of these
seem to depict usable alloys however, other than using the rhodium as
a plating medium.

Has anyone any further regarding ‘yellow rhodium’?

Cheers from
Don in SOFL.


#2

Don,

Much of the commercially advertised “yellow rhodium” is a
questionable thickness of rhodium plate on brass.

But there was a most interesting paper published in 1965 out of Los
Alamos National Laboratory, the only serious paper I have seen on
yellow rhodium. It points out that dirhodium trioxide Rh2O3 is yellow
in color and stable. It is insoluble in water or acids.

Amazingly, there is a scanned copy of this typewritten near-50yo
paper on the web! Find it here:

Radiochemistry of Rhodium
http://www.ganoksin.com/gnkurl/19n [pdf file]

Take a look at page 11 for the above that I remembered.
Take a look at page 9 for oxidization techniques.

I have a strong feeling this has nothing whatsoever to do with the
product you are seeking, but it demonstrates there are chemical
methods to make rhodium show a distinct yellow oxidized surface.

Mark Bingham
Fourth Axis