A bridal buyer in Manchester returned a run of 925 silver engagement rings after six weeks because the white-gold look had turned gray at the high points. The factory had plated at 0.1 micron, which is a flash coat, not a wear layer. On a ring that hits door handles and desk edges 50 times a day, 0.1 micron wears through in weeks. Rhodium plating is a process with a target thickness, a prep sequence, and a re-plating expectation; it is not a dip that makes silver permanently white. This guide covers the process parameters wholesale buyers should ask about.

Rhodium is a platinum-group metal plated electrolytically onto a prepared base (silver, white gold, or platinum) to produce a bright, hard, white surface. The plating bath is a dilute rhodium-sulfuric acid solution held at about 40-50 C, run at low voltage (0.5-2 V) for seconds. The thickness controls both whiteness and wear: consumer jewelry typically runs 0.25-0.5 micron, and a bridal ring that sells on a bright finish may run 0.5-1.0 micron. For material reference, see rhodium properties.

The prep sequence that decides plating life

Rhodium will not hide surface defects; it amplifies them. The prep sequence before plating is where plating life is won:

- Polish to a finer-than-consumer mirror, because the plate builds on the surface.
- Electroclean in a mild alkaline solution to remove oils and polishing compound.
- Rinse in deionized water.
- Optional flash gold or nickel strike to improve adhesion on silver (depending on nickel regulations; see below).
- Plate in the rhodium bath for the targeted seconds, then rinse and dry.

Sterling silver often gets a thin nickel or copper barrier flash before rhodium, because silver diffuses through rhodium and causes tarnish under the plate. Under EU REACH nickel rules, direct skin contact nickel release is restricted; wholesale rings shipped to the EU need either a nickel-free barrier or a documented compliance path. Check EUR-Lex REACH for current nickel limits.

Thickness and wear expectation

- 0.1 micron: flash coat, for display pieces or short-term white finish. Wears through in 2-6 weeks on a ring.
- 0.25-0.3 micron: standard retail plating. Holds 3-9 months on a ring shank.
- 0.5 micron: premium bridal plating. Holds 9-18 months before showing wear at high points.

Buyers should ask for the plating thickness on the work order, not just rhodium plated. A written 0.3 vs 0.5 micron spec changes the price per piece and the return rate. The re-plating cycle should be communicated to retail customers: rhodium is a maintenance finish, not a permanent one. A product page that says bright white finish with expected re-plating at 12 months sets a better expectation than one that promises a lifetime white surface, which the first worn shank will contradict. A written 0.3 vs 0.5 micron spec changes the price per piece and the return rate. The re-plating cycle should be communicated to retail customers: rhodium is a maintenance finish, not a permanent one.

Common plating defects

- Streaky or patchy white: inadequate electroclean, oil on the surface.
- Gray or dull plate: bath too cold, voltage too high, or plate too thin.
- Plate peeling or flaking: bad adhesion, usually from missing barrier flash or surface contamination.
- Yellow bleed-through at the shank after weeks: silver diffusion through a too-thin plate; needs a barrier flash and thicker coat.

See also final polishing before plating and fire scale removal; plating over either defect always fails.

How thick should rhodium plating be on a silver ring?

0.25-0.5 micron for retail, 0.5-1.0 micron for premium bridal. A 0.1 micron flash wears through in weeks.

Why does my rhodium turn gray after a month?

Wear-through at high points or plate too thin. Ask for 0.3 micron minimum and tell retail customers to expect re-plating as maintenance.

Is nickel under-plating allowed for EU sales?

Nickel release on skin-contact jewelry is restricted under REACH. Use a nickel-free barrier or document compliance before shipping to the EU.

Can rhodium cover fire scale or polish scratches?

No. Rhodium amplifies the surface. Both must be fully removed before plating or defects bleed through within months.

Rhodium is a spec, not a dip. We plate to a written micron thickness on every lot, use nickel-fr

Plating thickness and the re-plating promise

Retail customers often ask whether rhodium plating is a lifetime finish. It is not. A 0.3 micron coat on a ring shank wears through in 3-9 months at the high-contact points, and a 0.5 micron coat buys 9-18 months. Brands that promise lifetime bright should plan a re-plating service, not a thicker plate, because plate thicker than 1 micron starts to look milky and chips at edges. The honest spec on the product page is 0.3 micron retail or 0.5 micron bridal, with a note that re-plating is expected maintenance.

ee barriers for EU-bound orders, and log plating time per piece. If you are building a white-silver or bridal line, plan EU customs and compliance and review nickel release rules before the next production slot.