Why does jewelry turn your skin green?
Copper. Green marks are copper salts, formed when copper in the alloy meets sweat and skin acids, and brass is around two thirds copper. It is a deposit on the skin rather than a reaction in it, it washes off, and it is a fact about the metal rather than a sign of an allergy.
By SIAFRA
The green is copper. When copper in an alloy meets the salt and acid in sweat it forms copper salts, which are green and water soluble, so they transfer to skin rather than staying on the metal. Brass is roughly two thirds copper, which is why gold-plated brass is the usual source.
Two things follow from that, and both are reassuring. The mark is on you, not in you: soap removes it. And it is not an allergy. It is the composition of the piece, showing itself.
Why it starts months after you bought it
Because a new plated piece keeps the copper away from your skin, and then stops. The FTC puts the lifespan plainly: “Eventually, the gold plating wears away, depending on how the item is worn and the thickness of the plating.” Until it does, the base metal is sealed in. Once the layer thins at the points that rub, a ring band on the palm side, a chain at the back of the neck, the base is in contact with skin and the marks begin.
Which base metal is underneath is therefore the whole question, and the FTC is blunt about what usually is: “A base metal is a common and less expensive metal like nickel.” (FTC consumer guide to buying platinum, gold and silver jewelry)
Which bases mark, and which do not
| What is underneath | Green mark | Why |
|---|---|---|
| Brass or bronze | Likely once the plating thins | Both are copper alloys, and copper is what the green is made of |
| Copper | Yes, and quickly | No plating to delay it |
| Nickel or nickel-bearing alloys | Not usually green | The risk here is a rash rather than a stain. See below |
| Sterling silver | No | Silver tarnishes to a dark film rather than a green one, though sterling contains some copper |
| Stainless steel | No | Carries no copper for sweat to react with |
| Solid karat gold | No | Alloyed with copper in some colors, but not in a form that deposits this way |
Green stain, or an allergy?
They are different problems with different culprits, and treating one as the other is how people conclude they cannot wear jewelry at all.
- A green or greyish stain that wipes off, no itch. Copper. Cosmetic, harmless, and a statement about the alloy.
- Redness, itching, small blisters or a rash that outlasts the piece coming off. That is contact dermatitis, and the metal usually behind it is nickel, which the NHS lists among the metals that trigger allergic contact dermatitis. Worth a pharmacist or GP rather than a polishing cloth.
One widely repeated shortcut is worth correcting here. Jewellers often summarise the skin test as “genuine gold and silver will not react with the skin, so any problems will give away a fake piece.” (Jacqueline’s Fine Jewelry) The green half of that holds up. The irritation half does not, because white gold is sometimes alloyed with nickel, so a reaction is not proof that a piece is fake.
What actually slows it down
- Take plated pieces off before swimming, the gym and the shower, since chlorine, salt and soap all speed the wear along.
- Dry the piece and your skin after wearing it. The reaction needs moisture to carry the salts across.
- Rotate what you wear, so the same contact point is not rubbing daily.
- Treat clear nail polish on the inside of a band as a temporary patch rather than a fix. It wears off, and it does nothing about the alloy.
None of these change what the piece is made of. They buy time on a piece whose base metal was always going to decide the outcome.
Where SIAFRA sits on this
This is the reason SIAFRA specifies a steel base rather than a brass one. The pieces are specified as 18K gold PVD over stainless steel, and steel carries no copper for sweat to convert into a green deposit. Coating thickness has not been published as a measured number yet and will not be stated until the first batch is measured, which is a separate question from what the base metal is.
Read any plated piece the same way, ours included: find what the gold is sitting on, then decide.
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