All the reasons why gold turns dark

Figure 1. Tarnished gold jewelry

Any gold jewelry we wear can blacken over time: earrings, rings, pendants, chains, bracelets. It is undoubtedly very frustrating. Let’s consider the reasons why gold turns dark. Let’s try to understand whether it is possible to prevent or slow down this process, and how to do it.

Folk omens

In the people there are many explanations for this fact, and all of them are negative, you can even say “ominous”. According to omens, if dark areas appeared on the gold jewelry, it means that its owner was imposed spoilage or evil eye. Another common misconception is that the blackening of gold jewelry indicates that a serious disease is developing in the human body. In fact, all this is just a prejudice that has nothing to do with reality.

Scientific explanations

Let’s leave folk beliefs and go to the real reasons why gold turns black on the human body.

Gold darkens due to oxidation of the ligatures included in it

Pure gold is soft and malleable. To give it strength when making jewelry, additional components are added to the material: silver, nickel, copper, palladium, which are called ligatures. The ratio of gold and ligatures in the alloy is indicated by the grade. It shows how much pure gold is in 100 units of the alloy. If the jewelry is 585 grade, it means that there is 58.5% gold in this alloy, the rest is alloying additives.

Thanks to the addition of other metals, the jewelry can be given not only hardness and the ability to hold its shape, but also certain shades. For example, to obtain white gold, silver, palladium, nickel, and sometimes platinum are added to the alloy. Red or pink shade gives an admixture of copper.

Gold is a noble metal that does not oxidize. But other metals added to the alloy can oxidize. Therefore, the more impurities in the alloy, the higher the probability that the jewelry will blacken. For example, 375-grade gold is more likely to blacken than 750-grade gold because it has 62.5% impurities versus 25% impurities in 750-grade gold.

Gold can also darken if the ligature that makes up it is of poor quality. Or there are more impurities than the hallmark indicates. This is often the case with fakes, or if the manufacture of jewelry neglected to comply with technology.

Polishing paste darkens

Before selling gold jewelry is often covered with a special polishing paste. With it, the noble metal looks more beautiful, sparkles and shines. You will not see the remnants of this paste itself, but they may cause dark spots, not only on the jewelry, but also on the skin. For example, a dark rim will appear on the finger on which the ring was worn.

Fig. 2. Blackened finger from the ring

So there is nothing mystical about the darkening of the skin from wearing gold jewelry.

Gold darkens in contact with iodine or mercury

Dropping iodine on gold is one of the popular but highly questionable ways to test gold jewelry for authenticity at home. If you doubt the quality of the product, it is better to give it to a professional jeweler for examination. Iodine stains left at home will turn gray or darken, because iodine destroys the molecular structure of the outer layer of gold. These effects are irreversible; the jewelry will simply be ruined. Although traces of iodine can appear not only as a result of testing gold for authenticity, but also for other reasons.

For example, in a swimming pool or spa, the water often contains iodine particles. If you are going to visit any of these establishments, it is better to remove gold jewelry beforehand. There are also iodine particles in a number of perfumes and cosmetics. If such products get on earrings, rings or chains, jewelry can change its shade.

Sometimes cosmetics of dubious production and low quality contain mercury, a chemical element dangerous to human health. Mercury can cause not only blackening of gold by reacting with it, but also irritation on the skin. If gold jewelry has turned black as a result of contact with mercury, it cannot be restored.

Gold turns black due to pollution

The human body secretes sweat, and dead microscopic skin particles are also constantly separated. All this settles on jewelry in the form of dirt and makes it dull. Under a layer of greasy deposits, gold can darken considerably.

For example, there is an opinion that gold jewelry quickly darkens in people who eat a lot of meat. This is due to the fact that meat proteins contain nitrogen, which is released with sweat and reacts with alloying additives of gold alloys.

Fig. 3. Gold jewelry after cleaning

Preventing tarnishing

Gold tarnishing can be prevented, if not prevented, then at least delayed. To do this, follow a few simple rules:

• Do not wear jewelry when you clean the house and use household chemicals.
• Leave the gold at home if you are going to the pool, to the beautician or to spa procedures.
• Take off jewelry before applying cosmetics, creams, perfumes. Put it back on not immediately, but after some time.
• Remove jewelry every evening, wipe it with a flannel cloth.
• Periodically clean hard-to-reach places with cotton swabs, you can gently go over them with a toothpick with a thin piece of absorbent cotton wrapped around it.
• Do not wet absorbent cotton for cleaning gold with acetone, hydrogen peroxide. Gold from the reaction with these substances can oxidize, but it will not become cleaner.

Proper storage of gold jewelry

It is very important to store gold jewelry properly. For your jewelry, choose a padded jewelry box divided into sections. It is important to allocate it exclusively for gold jewelry and do not store there, even if in other compartments, costume jewelry or jewelry made of other metals. In the box should not penetrate the sunlight. If you do not have a special box, take any small box and put jewelry wrapped in a flannel cloth in it.