Why does gold jewelry change color?

Many people believe that gold jewelry never changes color.
However, it is not uncommon for a ring, necklace, or bracelet to:

• darkness
• turn reddish
• lose its luster
• reveals a different color

So, is it necessarily fake gold?
Not always.

Here's why some gold jewelry changes color and how to tell if a piece of jewelry is real gold.

Pure gold almost never changes color

Pure gold (24 karat) is a very stable metal:
✔ It does not rust
✔ It hardly oxidizes at all
✔ It does not tarnish

But in reality, most of the jewelry sold in Belgium is not made of pure gold. It is made from alloys.

Why is gold mixed with other metals?

Pure gold is:

• very soft
• fragile
• difficult to wear on a daily basis

Jewelry makers therefore mix gold with:

• copper
• money
• zinc
• perfect
• palladium

➡ This makes the jewelry more durable.

But these metals can react with:

• the air
• sweating
• humidity
• chemicals

And cause a change in color.

9K gold jewelry often changes color more quickly

This is one of the most common causes.

✔ 18K gold (750)

Contains 75% pure gold.
➡ Generally more stable.

✔ 14K gold (585)

Contains 58.5% pure gold.
➡ May tarnish slightly over time.

✔ 9K gold (375)

Contains only 37.5% pure gold.
➡ Contains significantly more added metals.

Result:
👉 9K jewelry is more likely to:

• go for it
• blush
• dull
• change the color

Gold plating: the most common cause

Many pieces of jewelry that change color dramatically are actually:

• gold-plated
• gold-filled
• gold-plated metal

The concept:
➡ a thin layer of gold covers a less precious metal.

Over time:

• the diaper wears out
• the metal underneath is visible
• the jewelry turns gray, copper-colored, or silver-colored

Some products speed up color change

Even genuine gold jewelry can react to certain products:

❌ perfume
❌ chlorine
❌ household cleaners
❌ seawater
❌ acidic sweat
❌ cosmetics

These reactions mainly affect:

• low-carat jewelry
• antique jewelry
• copper-rich alloys

Why does some jewelry turn red?

When the copper in the alloy oxidizes:
➡ the jewelry may take on a reddish tint.

This happens mainly on:

• 9K jewelry
• some antique jewelry
• heavily worn jewelry

Is jewelry that changes color fake?

Not necessarily.

Genuine gold jewelry may:
✔ tarnish slightly
✔ lose its luster
✔ change color slightly

But be careful:
👉 a major change can also reveal:

• gold-plated
• fake jewelry
• a low-gold alloy

How can you tell if a piece of jewelry is really made of gold?

At Agence de l’Or, we use several professional methods:

✔ Hallmark verification

• 750 = 18K
• 585 = 14K
• 375 = 9K

✔ Spectrometer analysis

Allows you to determine the exact composition of the metal.

✔ Touchstone and acid test

A professional method used to verify carat weight.

✔ Magnetic test

Gold is a non-ferrous metal and is never magnetic.
⚠️ Warning: jewelry that isn’t attracted to a magnet isn’t necessarily made of gold.

Can you clean tarnished jewelry?

Yes, sometimes.

A few simple tips:
✔ soft cloth
✔ warm soapy water
✔ avoid harsh cleaning products
✔ avoid toothpaste or abrasive products

⚠️ But if the color changes significantly:
➡ this may indicate that the plating is worn.

Where can I have my jewelry appraised in Belgium?

At Agence de l’Or, we offer free appraisals of your jewelry at our locations:

• Braine-l'Alleud
• Wavre
• Wavre Center
• Saint-Pierre-Woluwe
• Rixensart
• La Louvière
• Charleroi
• Uccle

✔ Free appraisal
✔ Professional analysis
✔ Transparent estimate
✔ No obligation

A change in color doesn't always mean it's fake gold

Gold jewelry may change color slightly due to:

• alloys
• wear and tear
• chemicals
• time

But a significant change can also reveal:
❌ gold-plated
❌ costume jewelry
❌ a low-grade alloy

The best way to be sure is still to get a professional assessment.

Stop by one of our stores to have your jewelry appraised for free.