Diamond that turned blue during rhodium plating

The jeweler had finished setting a princess cut stone in a platinum
mounting. He then was going to rodium plate the mounting. He was
using a different plating solution than he usually used. He used
the same procedures that he has used for years on rhodium plating a
mounting with a stone in it. After following his procedures to his
horror the diamond is now tinted a gun-metal blue. We know that
this is a coating, but URGENTLY need advise on how to remove it. We
called the manufacturer of the Rhodium plating solution who
suggested a chemical solution called hydroflouric acid. This
chemical can only be used in a high-grade laboratory setting.
Obviously this is not an option to us. All suggestions are welcome.

Lori Gregory
Gregory Jewelers

Diamond, unlike other conducts electricity very well. So
your friend probably plated it with Rhodium while he was plating the
mounting. Unfortunately Rhodium is difficult to dissolve. I am pretty
sure that it is NOT soluble in Hydrofluoric acid. My Chemistry
Handbook says it can be dissolved in a 50:50 mixture of concentrated
Sulfuric and Hydrochloric Acids. Another option may be Anodic
Stripping. Simply reverse the current in your plating bath. Make the
Diamond the Anode(+) instead of the Cathode(-). In either case, it
would probably be advisable to remove the Diamond first…Bob

That is trully amazing to be able to plate a Diamond, If the diamond
can be removed from the setting without much difficulty i would do
that, and use a mounted polishing wheel. like a blue silcone wheel.to
remove the coating or even a bench brush with some tripoli should
take off whatever is stuck to the diamond. I would also make sure
and verify that whatever the stone is that your cleaning is in fact a
Dia and not some type of synthetic. I suppose a remote possibility
might be it is a fracture filled diamond and the plating process
somehow damaged the filler material as it only would take a small
amout of color in the stone to alter the body color of a dimond.If
this is the case it would need to be sent to the original enhancement
company for replacement of the filler product.Also a chemical
stripping solution might be able to remove it ,these can be easily
obtained at any local jewelery supply house. still find it hard to
believe that that the actual stone is plated as the surface of a
diamond is so hard and smooth that any thing plated to it woud be
able to stick to the surface with any serious bonding strengh.
another possibility is that if the ring is channel set or bezel set
that the metal coming in contact with the stone was "overplated " or
is the gun metal blue color and is refelecting into the stone and
causing the blue hue. and in this case the Dia would more than likely
need to be pulled and the plating removed. Also please note
hydroflouric acid is a strong acid i believe it dissolves glass and
silica so caution should be used.

Good luck

Jeff Alverson

Hi Lory,

Hydrofluoric acid is used for etching glass. As long as you use it
carefully in a plstic container, there is no problem in working with


I suggest that you DON"T mess with hydrofluoric acid if you’re not
comfortable with dangerous chemicals…it is NASTY to flesh.

You certainly can remove the diamond and have a good diamond cutter
repolish it with VERY minimal weight loss.

I can recommend L.A. Diamond Factory (Mervin Hahn)
mervin1@earthlink.net in my building, if you don’t have a cutter you
use. David Barzilay, Lord of the Rings

One other possibility is having a faceter polish the ‘color’ off.
Assuming the color is just a surface layer of rhodium hasn’t etched
the diamond surface, the rhodium could probably be polished off by
most any faceter.

Good luck!


CAUTION! Hydrofluoric acid is extremely dangerous! A single drop
spilled on your skin will probably eat clear to the bone (or

Also, be completely sure that you do not breathe any of the fumes
(unless you think you can do without your lungs in the future!)


Hydrofluoric acid can be VERY VERY bad! Makes Sulfuric, Nitric,
Hydrochloric, etc. acids look like hand cleaner!! I once was pouring
some into a saucer of water to etch some glass and a tiny splash of
the dilute acid from the saucer landed on my hand (really tiny). I
immediately hosed it off and held bicarb on it. There was this very
small dot there on my hand. Shrug. Then it started to hurt and
inflame in an increasing circle till it got to like a nickel or a
quarter or such! I don’t remember how deep it went - plenty enough
to hurt- but I have heard of slightly larger burns going to the bone!
The guy (he was a front office guy cause the workers had gone home)
that filled the bottle for me ended up in the hospital - I never
heard how he made out because I never went back to buy more! I would
strongly recommend not messing with Hydrofluoric acid unless you
really know what you are doing! There are tamer products around for
etching glass, try a stained glass place. I don’t know if either
substance will etch rhodium off of a diamond.

Looking forward:
Alan Shinn
Experience the
beginnings of microscopy.
Make your own replica
of one of Antony van Leeuwenhoek’s microscopes.
visit http://www.mindspring.com/~alshinn/

ok someones gonna hate me but too bad he dosnt know where i live , i
am reasonably certain that the jeweller is not telling the truth .
the gun-metal blue coating was most likely caused by the ring being
heated up with the diamond in it , he was probably filling holes in
the band or resizing the ring . i assume it is 18ct white gold and
if he used hard gold solder the heat required for it to flow can
sometimes cause the surface to become “cooked” and almost every time
it will give a definate gun metal blue . It should be easy for most
diamond cutters to repolish . Any damage being done during rhodium
plating is extremely unlikely. He is probably just too embarrassed
to admit he messed up . PHIL