Have you ever been surprised when you took off a ring or necklace and your skin looked green? Don’t worry, this isn’t a bad reaction with your skin, the green color fades away too.
This is the Patina Effect — when jewelry naturally turns green with time.
What is the Patina Effect?
The patina effect is a color change in red metals caused by oxidation, specifically in copper.
The green color is a result of the metal coming into contact with water, oxygen, and carbon dioxide over time. This causes a coating to build on the surface. Yet, instead of rusting, it morphs into a beautiful blue-green color. And what’s really cool about the blue-green color is that it also makes the metal more resistant to further corrosion. In a sense, when it oxidizes, it actually becomes stronger and more durable.
Which jewelry metals change color over time?
Copper, brass and bronze will get the blue/green patina layer gradually
Jewelry that turns green on your skin may be made of copper, brass or bronze. These will react with air, sweat, lotions, soaps, and any other types of chemicals that we expose our skin to. With prolonged contact, the patina formed can actually stain your skin.
Let’s start with the most common one, copper. You can see the blue-green patina on statues and home ornaments made of copper.
Brass also behaves a lot like copper when exposed to air and water — it will take on a blue-green color. This is because brass is an alloy that’s usually made up of 67% copper and 33% zinc — so it behaves in a similar way over time.
Bronze is also composed of 88% copper and 12% tin. Both brass and bronze have a really high copper content, which is why they form that same patina when they oxidize.
How long does it take for them to turn green?
This is extremely relative. In very dry conditions, copper, brass or bronze can take up to 20 years to turn green. It also changes color in stages. At first, the copper will turn dull like a penny. Then brown, then darker brown, and finally it will start to turn green. It’s a beautiful ageing process.
Stainless steel, gold filled or plated jewelry, and sterling silver jewelry don’t change color. These are some “what you see is what you get” materials — no color change here.
Is green jewelry safe to wear? Yes.
It is totally safe. You won’t absorb enough through your skin to do any damage. Actually, some people claim that copper jewelry has health benefits. These include things like relief from headaches and arthritis, joint pain, and zinc deficiencies.
For one, the blue/green layer — the patina — adds a protective layer to the metal. Another neat thing about copper, brass and bronze jewelry is that it ages intentionally so the jewelry design gets a “classic” look the more you wear it.
Aging jewelry is beautiful too.
It’s still okay if you want to remove the green layer
There are many situations where you don’t want this patina. For example, you probably don’t want your skin turning green if you have jewelry with copper in it. Or you might just prefer the bright look of copper instead of the dull greenish color of the patina.
How to stop your jewelry from turning green
The simplest way to keep copper, brass, and bronze from turning green is to just clean it regularly. It can take several weeks for the patina to form under average conditions.
A very old-fashioned way of preserving copper is by polishing it with beeswax. It takes a bit of elbow grease, but it does a very good job of protecting the metal from moisture and oxygen.