Why Does
Jewelry Tarnish and how to prevent it

Many of us have experienced that moment when you take off your favorite piece of jewelry and a green or gray residue lingers behind. While a quick wash of the hands will usually cure a case of green fingers from jewelry, it can be annoying all the same. Sometimes you can pin it to a single piece (like Grandma’s vintage cocktail ring) or a specific behavior (like wearing jewelry while swimming). But other reasons your jewelry tarnishes can be a little harder to nail down.

Following our jewelry care best practices is a good place to start, for those hoping to keep their Moon Magic gemstone jewelry looking shiny and new. Getting to know what your jewelry is made of is another great way to determine if it will tarnish, how to prevent it, and what to do if it does.

Precious metals in their purest form are lovely to look at, but generally, they’re not great for functional jewelry. Pure gold (Au) and silver (Ag) are very soft and malleable, and would not hold up to daily wear and tear.

To create a more durable material for jewelry, gold and silver are often mixed with other metals to add strength. According to Encyclopedia Britannica, “Because pure gold is too soft to resist prolonged handling, it is usually alloyed with other metals to increase its hardness for use in jewelry, goldware, or coinage.”

“Most gold used in jewelry is alloyed with silver, copper, and a little zinc to produce various shades of yellow gold, or with nickel, copper, and zinc to produce white gold,” they explain. “The colour of these gold alloys goes from yellow to white as the proportion of silver in them increases; more than 70 percent silver results in alloys that are white.”

Similarly, rose gold jewelry is crafted from an alloy of yellow gold and copper to create the blushing pink hues it’s known for. Silver and zinc are also common additions to rose gold, though, we do not use nickel. While creating a distinctive color, alloyed metals also add durability to rose gold and white gold jewelry.   

Many cost conscious shoppers opt for gold plated or vermeil jewelry instead of pieces with higher concentrations of gold. Using a process called electroplating, gold or gold alloys can be added to a stronger base metal (like brass, copper, or sterling silver). Jewelry made with thin layers of this outer gold coating are sold as gold plated, while thicker layers (a min of 2.5 microns) are called vermeil. Vermeil jewelry is considered higher end than gold plated jewelry, is more durable, and contains a larger amount of precious metals than simple gold plating.

Is it karat, carat, or carrot? When it comes to understanding the value and purity of gold jewelry, we’ll stick to the first two (though carrots are pretty yummy). To understand the meaning of the word karat, we’re going to head back to elementary school math.

Karat is a term used to describe the proportion of pure gold in a gold alloy. Since pure gold is considered 24k (or 24 karat), the ratio of gold to other metals is determined by its karat rating divided by 24 (stay with us here). For example, 18k gold would be 18/24 or 75% gold. 

The karat system for measuring gold fineness dates back to Roman times, and is the standard in the US and UK. Many other countries are moving to a millesimal system of measurement, which (like 925 sterling silver) expresses the ratio of gold in an alloy with 1000 representing pure gold instead of 24. In Europe, you might see the hallmark 750 instead of 18k to identify a piece that is 75% gold.

The word carat can also be used to describe gold fineness, and is more common in the UK. In the United States, carat usually describes the weight of diamond jewelry and other precious gems. When used to measure gemstones, a carat represents 200 milligrams.

Karats are used to measure the fineness of gold. Pure gold is 24 karats. The word carat, however, is usually used to describe the weight of a gemstone. A single carat is equal to 200mg.

Now that we’ve refreshed our 4th grade fractions (and how they relate to gold fineness), you’ve got a better understanding of how jewelry is made and why it can tarnish. Pure gold and pure silver are extremely workable and not prone to much tarnishing under normal conditions. It’s those pesky (albeit helpful) strengthening metals that go into alloys that are the cause of most jewelry tarnish.

Environmental factors like pollution and humidity are also major players in tarnished jewelry. Depending on which metals are alloyed, some pieces of jewelry can be more reactive than others. You might have heard the term oxidization before - that’s the chemical reaction that happens when certain metals are exposed to oxygen in the atmosphere. In other words, even air plays a part in tarnishing jewelry, and that’s a pretty tough one to avoid.

Jewelry with copper tends to be pretty reactive to things like salt water, citrus fruits, and even sulfur that leeches out of packaging. Occasionally polishing your sterling silver jewelry and other pieces that contain copper will keep them in top shape. The bright side is, it’s a great excuse to pull out and admire all of your pretty jewels.

If you’ve opted for jewelry with a lower gold content for color, strength, or affordability, you’ll want to take a few precautions to keep it looking great. While pure gold is not as reactive to environmental factors as some materials, the other metals in an alloy may still cause your piece to tarnish.    

We recommend taking off your gold jewelry when showering, washing dishes, swimming, and exercising. Keep it safe from cleaners that contain chlorine bleach, and always apply your jewelry as a last step when getting ready (cosmetics and lotions can speed up the tarnish process).

Learning how to clean tarnished gold is all about reading those labels. If you are considering a commercial gold cleaner, make sure that it is specifically formulated for all of the metals (and gemstones) in your jewelry. When in doubt, use a soft toothbrush, mild soap, and warm water to bring back your gold’s shine.

Yes. Pure silver is not reactive to oxygen or water under normal conditions. According to Wikipedia, however, “It is attacked by common components of atmospheric pollution: silver sulfide slowly appears as a black tarnish during exposure to airborne compounds of sulfur.” These byproducts of burning fossil fuels can cause silver to turn dark. And exposure to oxygen, salt, and moisture can cause a discoloration in 925 sterling silver, which is 7.5% copper.