You take a ring off after a long day and there is a green band where it sat. Nothing hurts, nothing looks damaged, but the mark will not rinse away in one pass under the tap.
The answer is more boring than it looks, and the fix is mostly about habits.
What the green actually is
Most affordable jewelry contains copper, either as the main base metal (brass is copper and zinc) or in an alloy underneath a plating. Copper reacts with the acids and salts in sweat to form copper salts, which are green. Those salts transfer to your skin.
That is the whole mechanism. It is a chemical reaction between metal and skin, not corrosion, not dirt, and not evidence that a piece is poor quality — solid sterling silver contains copper too and can do exactly the same thing.
The mark is on the surface of your skin and washes off with soap and water. It is not absorbed and it is not a stain.
Why it happens to some people and not others
Skin chemistry varies more than most people realise. The main factors:
- How acidic your sweat is. This varies person to person and changes with diet, medication, hormones and stress.
- How much you sweat. Heat and exercise both increase it.
- Lotions and perfumes. Many contain acids or alcohols that accelerate the reaction.
- Humidity. Damp climates and summer make it far more likely.
This is why one person wears a brass ring for a year with no mark and another gets a green line the first afternoon. Neither ring is different.
How to stop it
Keep a barrier between metal and skin
The reaction needs contact. A thin coat of clear nail polish on the inside of a ring band or the back of a pendant is the cheapest fix that works. It wears off and needs redoing every few weeks, but it costs almost nothing.
Keep the piece dry
Take rings off before washing hands, showering, swimming and exercising. Water plus sweat plus copper is the exact recipe.
Last on, first off
Jewelry goes on after lotion and perfume have dried, and comes off before anything else.
Wipe after wearing
Ten seconds with a soft dry cloth removes the sweat before it sits on the metal all night.
Choose the metal deliberately
If it happens to you consistently, sterling silver and stainless steel react far less than brass. Steel in particular is close to inert against skin. Every listing on this site states the material, so you can filter for it before you buy rather than after.
A separate thing worth knowing: nickel
Green marks and a nickel reaction are not the same problem. A green mark is cosmetic and washes off. A nickel reaction shows up as redness, itching or a rash that stays after the piece comes off.
Nickel is present in many base-metal alloys used in fashion jewelry, including under plating. If you know you are sensitive to it, read the material line on the listing and email us if it is not specific enough. If you get a persistent skin reaction to a piece, stop wearing it and speak to a healthcare professional — we are not qualified to advise on that and we will not pretend otherwise.
The short version
Green skin is copper meeting sweat. It is harmless, it washes off, and a clear-polish barrier plus taking the piece off around water handles it for almost everyone.
Related: caring for plated jewelry.