Does Gold Rust?

Many metals rust, corrode, or lose their shine when exposed to air and moisture, but what about gold? One of the greatest features of pure gold is its corrosion-resistance, but does it really never rust or tarnish? And if not, why do some gold items become discoloured or develop red spots over time?

In this article, we share what to know about gold and rust, including why gold is resistant to corrosion, how alloys affect gold’s durability and appearance, and what you can do to prevent tarnishing or red spots on your gold items.

What is rust?

Rust is a chemical process that happens when certain metals react with oxygen or water. Over time, this process can cause a metal to deteriorate and leave behind visible damage – it’s what causes iron to turn reddish-brown and flakey.

Metals that don’t react with oxygen are called ‘noble metals’ while those that do are known as ‘base metals’. Pure gold is the most noble of all the metals, which means it doesn’t react with oxygen or water and will never corrode under normal environmental conditions. That’s why ancient gold jewellery and coins unearthed from archaeological sites often look the same as they would have thousands of years ago.

Rust vs corrosion: What’s the difference?

Rust is a specific type of corrosion that affects only iron and iron-based metals (like steel). When these metals come into contact with oxygen and moisture, they go through a chemical reaction known as oxidation. This produces iron oxide – in other words, rust – which appears as a reddish-brown coating. Over time, rust flakes away and weakens the metal underneath.

Corrosion is a much broader term that refers to metals gradually breaking down through reactions with their environment. Each metal corrodes differently. For example, aluminium forms a whitish oxide layer while copper develops a greenish patina. Unlike rust, corrosion doesn’t always deteriorate a metal – it can sometimes even act as a protective barrier that stops further damage.

Why do some metals rust and others don’t?

The reason why some metals rust and others don’t has to do with how they react to oxygen and water. Some metals, like lithium, are so reactive that they must be stored in oil to stop them from breaking down when exposed to air. Other metals, like copper and aluminium, react more slowly. Instead of flaking away, they form a thin oxide layer that acts as a barrier against further corrosion. This is why copper is often used in water pipes and why aluminium doesn’t disintegrate, even though it corrodes.

On the other hand, noble metals like gold, silver, platinum, and palladium are extremely resistant to chemical reactions, so they don’t corrode or rust like other metals do.

Why doesn’t gold rust?

Gold doesn’t rust because its atoms are stable and don’t bond easily with other elements like oxygen. This means that pure gold will never rust or break down, no matter how long it’s exposed to air or moisture.

What are the unique properties of gold?

Besides gold’s resistance to rust and corrosion, it has a whole heap of other unique properties that make it so prized. These include:

• Malleability & ductility: Gold can be hammered into sheets so thin they’re almost transparent, or stretched into fine wires without breaking.
• Non-reactive: Gold isn’t affected by most acids and chemicals that would normally damage other metals. The only exception is aqua regia, a mix of nitric acid and hydrochloric acid that can dissolve gold.
• Conductivity: Gold is an excellent conductor of both heat and electricity, which is why it’s often used in electronics and aerospace industries.

Do gold alloys corrode?

While pure gold doesn’t rust or corrode, gold alloys – mixtures of gold with other metals like copper or silver – can tarnish over time.

For example, rose gold is made from an alloy of gold and copper, which oxidises and can cause subtle darkening or tarnishing over time. White gold often contains nickel, which can react with air or moisture unless the surface is plated with rhodium.

See: What is White Gold and What are its Characteristics?

Many gold coins are also made from alloys. For example, the Royal Mint uses copper and silver in its 22-karat gold Sovereign coin. These metals are added to make the coins extra durable and scratch-resistant, but they can also cause it to tarnish over time.

What can make gold tarnish?

The degree to which gold coins, jewellery, or other decorative items tarnish depends on their purity. Purity is measured in carats (or karats), where pure gold is 24 carats. It’s also measured in fineness, where gold content is expressed in thousandths (999 fine being almost pure). So gold items with lower purity may be more likely to tarnish.

Read More: Gold Purity, Fineness, And Karat – What Is It And How To Check It

It also depends on what metals are mixed in with the gold. White gold (alloyed with platinum or palladium) tends to be more corrosion-resistant compared to rose gold, which contains copper.

Gold alloying is all about balancing durability with colour. For example, nine carat gold is tough and affordable but can tarnish more easily and lacks the brilliant lustre gold is known for. 22-carat gold, on the other hand, has a bright yellow shine but is too soft to craft intricate jewellery. Pure, 24-carat gold is completely resistant to rust and tarnishing, but is too soft for everyday wear, which is why it’s mainly reserved for bullion coins or bars.

Continue Reading: Gold Alloys Guide – Composition, Types & Uses

Can tarnishing affect the value of gold?

Tarnishing might sound like a bad thing, but it doesn’t necessarily affect the value of gold items. In some cases, it can even add character to a piece that makes it even more special and sought-after. For example, certain types of gold jewellery – especially vintage designs – can look more authentic with a touch of tarnish, increasing its appeal and market value.

When it comes to gold bullion bars and coins, tarnish doesn’t really affect the resale value of gold. Firstly, bullion bars are usually made from 99.99% pure gold so they’re extremely unlikely to tarnish in the first place. Secondly, even if a piece does tarnish (such as a 22-carat gold Krugerrand coin), its gold content will remain the same, and so will its market value.

With collectible coins, however, the situation is different. These coins are valued not only for their gold content but also their rarity, condition, and historical significance. In these cases, tarnishing may affect how desirable they are to collectors and reduce their resale price.

See: Bullion vs Numismatic Coins

What causes red spots on gold?

Even though gold doesn’t rust, it can sometimes get reddish or brown spots. These usually appear on gold items alloyed with copper – mostly jewellery that’s worn frequently and exposed to the skin. Because copper is more reactive than gold, it can oxidise when exposed to air, sweat, and moisture and create reddish stains or spots.

In rare cases, red spots can even develop on 99.99% pure gold bullion coins and bars. This is usually due to the tiny amounts of copper or silver that remain in the gold or are transferred during the minting process. Even just 0.01% of other metals can react with oxygen or sulphur in the air and produce small discoloured patches on the surface.

Red spots might seem concerning, but it’s not usually anything to worry about. These marks are purely cosmetic and won’t affect the intrinsic value of your gold items.

How to clean and prevent tarnish and red spots on gold

First, we want to make it clear that you shouldn’t try to clean pure, 24-carat gold coins or bars at all. Removing them from their official sealed packaging or trying to polish them can reduce their value and might leave scratches that dealers and collectors consider damage. If you own gold bullion for investment purposes, your best option is to keep it sealed and stored securely.

That said, if you want to protect gold jewellery or other items from tarnish and red spots, here are some tips:

• Handle with care: Always wash your hands and wear clean, cotton, lint-free gloves when handling pure gold and avoid latex gloves as they can leave behind residue.
• Limit touching: The less you touch your gold, the lower the chance of transferring oils, sweat, or other contaminants that can lead to discolouration.
• Keep in storage: Gold should be stored in a cool, dry, and airtight place away from silver or other metals that may already be corroding (this can increase the risk of surface reactions).
• Use gentle methods: Wipe gold regularly with a soft, lint-free cloth to remove oils and dirt. If you want a deeper clean, soak your items briefly in warm water then pat dry with a towel.
• Avoid harsh chemicals: Don’t use any household cleaners, bleach, or chlorine as these can damage alloys and speed up tarnishing, especially if your pieces contain copper.

Does gold rust? FAQs

Can gold damage over time?

Yes, even though pure gold doesn’t rust or corrode, it’s very soft and can scratch or dent if worn regularly. Gold alloys are more durable but can tarnish or discolour if exposed to moisture or chemicals.

What causes red spots on gold?

Red spots can form on gold alloyed with copper or other metals, which can oxidise over time and leave behind reddish or orange marks on the surface.

Does salt water make gold rust?

Salt water won’t rust pure gold, but it can speed up tarnishing in gold alloys (e.g. gold mixed with copper or silver).

Does fake gold rust?

Yes, fake gold is often made with base metals that can rust when exposed to air or moisture.

Does gold rust in chlorine?

Pure, 24-carat gold won’t rust in chlorine, but lower carat gold (e.g. 18k, 14k) can discolour over time.

Summary: Does gold rust?

Pure, 24-carat gold does not rust or corrode, but if you own gold jewellery items alloyed with copper, silver, nickel, or other metals, then they may tarnish or discolour over time.

The good news is that, when it comes to investment gold, tarnish and discolouration rarely affect an item’s intrinsic worth. Bullion bars and coins are valued for their gold content and not their appearance, so pure, 24-carat gold remains a trusted store of wealth no matter what it looks like.

If you’d like to invest in gold, you’re in the right place. At StoneX Bullion, we offer a wide range of 24-carat gold bars and coins, as well as bullion alloyed with other metals, like the American Gold Eagle. Explore our collection of gold, silver, and other precious metal bullion today!