Gold karats and nickel: 10k, 14k, 18k

What a karat number tells you

We work from published documents and have not tested any jewellery. This page covers one question: what a gold karat mark does and does not say about nickel.

DermNet (retrieved 2026-11-14) says gold for jewellery is typically measured in karats, also spelt carats, and gives these figures: 24 karat (pure gold) is 99.9% gold plus 0.1% other metal, 18 karat is 75% gold, 12 karat is 50% and nine karat is 37.5%. The rest of the piece is other metal: “To make up the rest of the metal, gold is alloyed with other metals.”

Two limits apply. First, we could not retrieve a standards or regulator text that defines karat as parts of gold per 24. The figures above fit that idea (18 out of 24 is 75%), but we cite them to DermNet only. Second, DermNet’s figures skip 10 and 14 karat, so we do not state their gold content here. A lower karat number means a smaller share of gold and a larger share of other metals; beyond that, the sources we read are silent on what those metals are in any given 10k or 14k piece.

What the “other metals” can be

DermNet says gold “can be alloyed with many different types of metals which alter its hardness, colour and other properties.” Its example: “yellow gold may be alloyed with silver and copper, while white gold is usually alloyed with nickel.” It adds that many people who believe they are allergic to gold or silver jewellery are allergic to nickel, which can occur as a trace element in gold or silver, or “has been used in the manufacture of gold jewellery to whiten and strengthen the piece.”

So the claim “14k gold contains nickel” is neither always true nor always false on these sources. It depends on the alloy, and the karat stamp does not name the alloy. For people with nickel allergy, DermNet frames the question this way: which metals is your gold jewellery alloyed with?

White gold

DermNet says white gold is usually alloyed with nickel, and that “even white gold with nickel is often rhodium-plated to make it appear whiter and shinier,” which leaves the nickel alloy in contact with skin once the plating goes. It says the initial plating protects against any nickel in the gold, but “it eventually wears off over months or years.” Alternative white gold alloys based on palladium, silver and other white metals are available, it says, but palladium alloys cost more than nickel ones. Our guides on rhodium plating and skin reactions and palladium in white gold cover those two metals.

A 1996 study in the British Journal of Dermatology (PMID 8746329) patch-tested a range of nickel-containing alloys and platings on 100 nickel-sensitive people and 20 nickel-negative controls. Its abstract reports that nickel interliners under gold, silver or chromium plating, nickel-silver and “some white-gold alloys” caused positive patch-test reactions, while three non-plated stainless-steel alloys caused none. It does not say which white-gold alloys or karats, so it cannot be used to rank karats.

A 2016 laboratory paper (PMID 27664322) measured metal release from discs of a white gold alloy in two artificial sweat solutions, one of them the EN 1811 solution used for REACH nickel compliance testing. The abstract says similar levels of metal were released in both; it does not report the alloy’s composition or nickel figures, so we draw nothing further from it. How such testing works is covered in how nickel release is tested.

Does a higher karat help?

DermNet’s general advice is to look for jewellery made of stainless steel, at least 18 karat gold, sterling silver or polycarbonate plastic, and it says to assume all metal jewellery has some nickel unless it is stainless (surgical) steel, 18- or 24-karat gold, sterling silver or pure platinum. That is attributed guidance. We found no source with measured nickel content or reaction rates across 9, 10, 14 and 18 karat gold, so we cannot tell you how much lower the risk is at each step, or that any karat assures nickel absence. “At least 18 karat” is DermNet’s rule of thumb, not a legal standard. Our pages on what hypoallergenic jewelry means and nickel allergy and jewellery cover how loosely the claim is used.

Gold allergy is a separate question

Some people react to gold itself. DermNet’s gold allergy page says gold has been found in some patch test series to be the second most common metal allergen after nickel, and that those with gold allergy are often also allergic to nickel and cobalt. It also says copper in low-carat gold jewellery can cause gold release; it does not explain the mechanism or define low-carat.

A 2000 study of 449 people with a history of jewellery reactions (PMID 10863220, Journal of the American Academy of Dermatology) reports that gold allergy coexisted with nickel sensitivity in 10% of cases, and that an extended metal series picked up more nickel reactions than the standard series alone (61% against 38%). A 2022 review (PMID 36498546) lists gold among metals that have lately attracted attention beyond nickel, chromium and cobalt. Which metal is behind a reaction is a patch-testing question for a dermatologist.

What the rules say

The EU’s REACH restriction on nickel (Annex XVII, entry 27, consolidated text retrieved 2026-11-14) sets limits that apply by material-neutral release rates. It says post assemblies inserted into pierced ears must release less than 0.2 μg/cm²/week, and that articles in direct and prolonged skin contact must not release more than 0.5 μg/cm²/week, including coated articles over a period of at least two years of normal use. The restriction speaks of nickel release, not karat, so a gold item can meet it on release without being nickel-free. A 1996 review (PMID 9007370) notes that the 0.5 limit is one below which a minority of nickel-allergic people will react, but “it is not safe in every nickel-sensitive individual.” Our EU nickel directive guide goes further.

Label names

The EU glossary of common ingredient names (Decision (EU) 2019/701) lists GOLD (entry 9986), PALLADIUM (entry 16356) and SILVER (entry 22738). We found no exact entry for NICKEL, RHODIUM or COPPER in the glossary text. Jewellery is not a cosmetic, so these names are shown for completeness and do not govern how a jeweller labels alloy metals.

Practical reading of a listing

This is a reading of what the sources imply, not medical advice. A listing that says only “14k gold” or “10k gold” has not told you the alloy. Useful questions for a maker are: what are the alloy metals, is the white colour from nickel, palladium or plating, and does the piece meet the EU nickel release limits. For plated, filled and vermeil pieces, see gold plated vs gold filled vs vermeil. Broader choices are in our guides to nickel-free wedding rings, platinum and sterling silver, and a worked product list is on hypoallergenic gold earrings and nickel-free earrings. Hub: Ingredients & materials.

If you are reacting to jewellery, ask a dermatologist or an allergy society. Diagnosis and treatment are clinical matters.