"Plated" is not a single condition. A piece with 0.1 micron of gold and a piece with 2.5 microns of gold both read as "gold plated" on a spec sheet, but they age completely differently. Thickness controls wear rate, nickel breakthrough, color consistency, and whether a piece survives a year of daily wear. Buyers who understand how the number is measured stop arguing about price and start arguing about spec.

The units: microns versus microinches

The industry quotes plating in microns (μm) in most of the world and microinches (Êin) in US retail. One micron equals 39.37 microinches. A typical "fashion" gold flash is 0.1-0.25μm (4-10Êin). "Regular" gold plate runs 0.5-1.0μm (20-40Êin). Heavy or "commercial" plate is 2.5μm and up (100Êin+). Vermeil-style heavy gold electroplate can reach 5-10μm. These are the bands buyers should be negotiating against.

X-ray fluorescence (XRF): the non-destructive standard

Most modern QC floors use an XRF spectrometer. It fires X-rays at the surface, reads the fluorescence of the plated metal, and calculates thickness from the attenuation through the layer. XRF is non-destructive, fast (10-30 seconds per spot), and can read gold over silver, nickel, brass, or steel. It also tells you the karat of the plate — useful because "gold plated" can mean 10K, 14K, or 24K deposit, which changes color and hardness. Limitation: XRF struggles on very thin deposits below ~0.05μm and on oddly shaped surfaces where the angle changes.

Beta backscatter: the older bench method

Before XRF became affordable, plating shops measured with a beta backscatter gauge. It fires radioactive beta particles at the surface and counts how many bounce back; denser plate attenuates the signal differently. It is reliable, cheap, and still in use on older lines, but it requires a known reference foil for the exact substrate and plate alloy, and it is sensitive to geometry. Many factories still keep one for spot checks alongside XRF.

Coulometric (strip) testing: the referee method

When XRF and beta disagree, a coulometric test settles it. A fixed area of plate is dissolved electrochemically, and the charge used to strip it back to the substrate is converted to thickness. This is destructive — you ruin the test spot — which is why it is reserved for sampling, not 100% inspection. It is also the method used to calibrate the non-destructive gauges.

Why thickness varies across one piece

Electroplating is not uniform. High-current edges — prong tips, outer shank, bracelet edges — build up thicker plate; recesses and inner shanks build up thinner. This is why a ring can test at 1.0μm on the shoulder but 0.3μm under the prong. When you specify a minimum thickness, insist on the thinnest allowed reading, not the average. A common clause is "minimum 0.5μm over 90% of visible surface, no point below 0.3μm."

The underplate matters as much as the topcoat

What sits between the base metal and the decorative gold or rhodium is where durability is actually built. A typical stack is copper strike, then nickel, then gold. The nickel layer provides a smooth, hard barrier and prevents silver or brass from diffusing up into the gold. Skip the nickel and silver tarnishes through the gold within weeks. Nickel-free plating uses palladium or an electroplated bronze barrier instead, at a higher cost and slightly lower wear resistance. Buyers in EU, California, and other nickel-restricted markets need to know which barrier they are buying, because "nickel-free" is a process decision, not a label you can add at the end.

How plating actually wears

Plate does not wear off evenly. It thins first at high-friction points: the inside of a ring shank, the back of a pendant that rests against skin, the edges of bracelet links. Under an XRF these spots read half the thickness of a protected surface. This is why a 1μm plate can look heavy on a display piece yet wear through in six months on a ring that rubs against a desk all day. The rule of thumb for retail-facing items: fashion plate 0.1-0.25μm is for occasional wear, 0.5-1μm is for everyday rings, and anything marketed as "lifetime" plating should be 2.5μm or heavier.

What to specify on a PO

  • Plate metal and karat (e.g. 0.5μm 14K gold over sterling).
  • Minimum thickness measured at the thinnest functional area, not the average.
  • Pretreatment: struck on nickel or copper? Nickel-free is a different process chain.
  • Over-rhodium? White-gold and silver items are often rhodium flashed — call that out separately.
  • Acceptance: XRF reading on X sample pieces per lot, tolerance ±20%.

Buyers who put these clauses in writing stop receiving pieces that look right on arrival and tarnish through at the high-wear points six months later. A plating spec on a PO is not a technical luxury; it is the line between a repeat customer and a returns ticket. For the underlying metal preparation that precedes plating, our notes on surface finishing steps cover the prep side.

EU-wide limits on nickel, lead and cadmium in jewellery are set by the REACH Regulation (EC) No 1907/2006 on EUR-Lex.

Frequently Asked Questions

What gold purities and platings do you offer?

Solid 10K, 14K and 18K, plus gold-filled and vermeil. Plated fashion lines use 1–2 micron PVD over brass or 316L.

How do I avoid mislabeling gold products?

Label by construction: solid, gold-filled, vermeil or plated. Mislabeling plated as vermeil is the most common compliance complaint in this category.

Can you stamp karat marks?

Yes. Every solid-gold and vermeil piece is stamped with karat and maker marks, which supports customs and resale claims.

What is the MOQ for gold lines?

50 pieces per design for stock settings; custom CAD work starts at 100 pieces.