While typical tarnishing makes gold darker due to corrosion, an orange appearance on your gold jewellery is usually caused by specific surface reactions or corrosion of the other metals (like copper) alloyed with the gold, rather than the process that causes standard dark tarnish.
Understanding Gold Alloys and Discolouration
Pure 24k gold is very soft. Jewellery is typically made from gold alloys, such as 18k or 14k, where gold is mixed with other metals like copper, silver, zinc, or nickel to increase durability and modify colour. The presence of these other metals means that while gold itself is highly resistant to chemical reactions, the alloy as a whole can still be affected by its environment.
What Causes Gold Jewellery to Discolour?
Discolouration often occurs when the metals alloyed with gold react with chemicals or compounds they encounter. This can include substances found in the air, on your skin (like sweat or oils), or in products you use (like cosmetics, lotions, cleaning supplies, or pool chemicals).
Typical Tarnishing vs. Orange Colour
Experts describe a specific process that leads to the common form of tarnishing in gold alloys:
- Tarnishing occurs because of corrosion.
- When an 18k or 14k gold piece tarnishes, it typically gets a little darker in color.
- This most common form of corrosion is seen as the result of exposure to oxygen, though reactions with sulfur compounds (forming sulfides) are also a significant cause of black tarnish, especially on alloys containing silver.
- Because of exposure to elements in the environment, tarnishing will be inevitable at some point.
However, the typical tarnishing described above results in a darker, often black or grey, appearance, not an orange one. An orange colour suggests a different kind of surface phenomenon or corrosion primarily involving the other metals present in the alloy.
Possible Reasons for an Orange Appearance
If your gold jewellery appears orange, it could be due to several factors:
- Corrosion of Copper Content: Gold alloys, especially those intended to be yellow or rose gold (like some 14k and 18k options), contain copper. Copper corrosion can result in reddish, brownish, or even greenish compounds, depending on the specific reaction. What you see as "orange" might be a particular form of copper oxide or other copper corrosion product on the surface.
- Surface Residues: Certain chemicals, cosmetics, or environmental pollutants can leave a sticky or discoloured residue on the metal surface that is orange in colour.
- Plating Issues: If the item is gold-plated over a base metal, damage to the plating could expose the underlying metal, which might corrode or discolour. However, 18k and 14k items are usually solid alloys, not plated, unless specifically stated.
Addressing the Orange Discolouration
If your gold jewellery has turned orange, you can try these steps:
- Cleaning: Often, surface discolouration can be removed with gentle cleaning. Use warm water and a mild, non-detergent soap (like dish soap) and a soft brush (like a toothbrush). Rinse thoroughly and dry with a soft cloth.
- Professional Cleaning: For stubborn discolouration, a professional jeweller has access to specialized cleaning solutions and equipment that can safely remove surface corrosion or residues.
- Check for Residues: Ensure you rinse your jewellery thoroughly after wearing it, especially if it has come into contact with lotions, perfumes, or cleaning products. Store jewellery away from moisture and chemicals.
If cleaning does not resolve the issue, or if you are concerned about the piece, consult a reputable jeweller who can assess the specific type of metal and the cause of the discolouration.
