The mesmerising touch
Rhodium is a platinum-group metal and one of the rarest things a jeweller ever puts on a piece. A coat measured in fractions of a micron changes what the piece looks like, what it survives, and in one respect who can wear it.
It is gold alloyed with palladium, nickel or silver — and gold is stubbornly yellow. However good the alloy, an unplated white gold ring reads slightly warm, faintly grey, a little tired. Rhodium is what people are actually seeing when they call white gold white.
Rhodium is among the most reflective metals there are, and it does not tarnish or oxidise in air. The brilliance is the metal itself rather than a lacquer over it, which is why it looks like depth rather than like coating.
Gold and silver are soft. Rhodium is not. The plate takes the daily scuffing that would otherwise dull the piece — for as long as the plate lasts, which is a matter of how thick it was laid.
Rhodium contains no nickel and is biocompatible. On a white gold alloy that does contain nickel — and many do — a sound coat is what stands between that nickel and a wearer who reacts to it. This is the part of plating that is not cosmetic at all.
The piece hangs on the cathode in a rhodium bath, a low current is passed, and the metal deposits. The whole plating step is quick. Almost all of the work — and all of the difference between a good job and a bad one — happens before the piece ever reaches the bath.
Thickness
Standard coat
0.75 – 1.0 micron
What a piece meant to be worn should carry.
Heavy coat
up to 2.0 micron
For a piece that will take punishment. Past this it stops helping.
Too thin
Too thin and the alloy underneath begins showing through within months — a ring goes yellow-grey at the shank first, where the hand wears it.
Too thick
Too thick and the layer becomes brittle and crazes. More is not better; correct is better.
A micron is a thousandth of a millimetre. Nobody is going to see the difference across a counter — which is precisely why it is the easiest corner in this trade to cut, and why we would rather write the number down than be vague about it.
Same metal, same bath chemistry family, five completely different intentions.
White gold rings, silver, diamond settings
Traditional sets, bangles, temple work, borders
Contemporary pieces, second tone in two-tone
Oxidised looks, diamond contrast, men’s pieces
Temple jewellery, carved and traditional work
It is a fair question, we will answer it in microns, and any plater who will not is telling you something.
Kanchwala Building, 3rd Floor, Room No. 28, 63 Dhanji Street, Zaveri Bazar, Mumbai 400003
