Why jewellery tarnishes and what actually prevents it

Why jewellery tarnishes and what actually prevents it

Most people notice tarnish before they understand it.

A necklace darkens slightly along the chain.
A ring develops a warmer tone where it rests against the skin.
A silver piece that once looked bright becomes subtly muted.

The change often appears gradual, almost invisible from one day to the next.

Eventually the question arises.

Why does jewellery tarnish in the first place?

The answer has less to do with time and more to do with chemistry.

What tarnish actually is

Tarnish is not dirt.

It is a chemical reaction between a metal and elements in its environment.

When certain metals are exposed to oxygen, moisture, or sulphur compounds in the air, the surface begins to react. Over time this reaction forms a thin layer of oxidation.

This layer changes the appearance of the metal.

Silver, for example, reacts with sulphur in the air to form silver sulphide, which appears as a darker patina across the surface.

This process is entirely natural and occurs with most metals.

The speed at which it happens depends largely on the metal itself.

The tarnish risk of metals

The pattern becomes clearer when you look at the composition of these metals.

Copper and brass contain reactive elements that oxidise quickly.

Gold, by contrast, is one of the least reactive metals on earth, which is why it has been used in jewellery for thousands of years.

Why Gold Jewellery Rarely Tarnishes

Pure gold is chemically stable.

Unlike copper or silver, it does not react easily with oxygen or moisture.

This is why solid gold jewellery can remain unchanged for generations.

However, pure gold (24k) is extremely soft, which makes it impractical for most jewellery.

Instead, gold is usually alloyed with other metals to increase durability.

Common jewellery alloys include:

• 18k gold (75% gold)

• 14k gold (58.5% gold)

Because these alloys contain other metals such as copper or silver, they can occasionally develop slight patina over long periods, but they remain highly resistant to tarnish compared with other materials.

Why flash plated jewellery can tarnish faster

Gold plated jewellery behaves differently because the gold layer is extremely thin.

When the plating gradually wears away through friction or washing, the base metal beneath becomes exposed.

That base metal is often brass or copper, both of which oxidise relatively quickly.

This is why plated jewellery may begin to appear darker or discoloured after extended wear.

The gold itself is not tarnishing. The underlying metal is simply becoming visible.

The role of plating thickness in preventing tarnish

One factor that significantly influences durability is the thickness of the gold layer.

Standard gold plating may measure less than 1 micron.

Gold vermeil typically measures 2.5 microns or more, which means the gold layer takes much longer to wear through.

Morgan & Äya jewellery uses up to 2.5 microns of 18k gold over sterling silver, creating a gold vermeil finish designed for regular wear.

Because the gold layer is substantially thicker, it protects the metal beneath for a longer period of time.

Every day things that can accelerate tarnish

Several common environmental factors influence how quickly jewellery changes appearance.

Moisture

Water alone is not always damaging, but repeated exposure combined with soap can gradually affect certain metals.

Skin chemistry

Natural oils and perspiration vary from person to person and can influence how metals react over time.

Air pollution

Urban environments contain higher levels of sulphur compounds, which accelerate tarnish on silver and copper-based alloys.

Cosmetics and perfume

Many beauty products contain chemicals that can react with metals.

How to slow down or reduce tarnish

While no metal remains completely unchanged forever (that's right, even stainless steel!), a few simple habits can significantly slow the process.

• Store jewellery in a dry place

• Avoid direct contact with perfumes and cleaning products

• Remove rings when using harsh chemicals

• Clean pieces gently with a soft cloth

These small routines help preserve the surface finish of most jewellery metals.