Jewel How

Why Does My Amethyst Have Black Spots

Amethyst is a purple variety of quartz. The color comes from iron and other impurities. The most valuable amethysts are a deep purple, but they can be light or dark purple, too. Some amethysts have black spots on them. These spots are called inclusions. Inclusions are small crystals or other minerals that got trapped in the quartz while it was forming.

Why Does My Amethyst Have Black Spots

Causes of Black Spots

There are many possible reasons why an amethyst might develop black spots.

Exposed to Too Much Light

Amethyst is a violet variety of quartz that ranges in hue from pale to intense purple. The color comes from ferric iron impurities. Amethyst may develop black spots due to too much light exposure. The black spots are caused by the oxidation of the iron impurities. Over time, these black spots may grow and spread, resulting in an overall discoloration of the amethyst. If you have an amethyst with black spots, it is best not to expose it to any more light.

Not Properly Cleaned or Stored

When an amethyst is not properly cleaned or stored, it may develop black spots. This is because the dirt and oils on the surface of the gem can cause it to oxidize. When this happens, the black spots will become more pronounced and may even spread. If an amethyst has black spots, it is still considered to be a valuable gemstone, but its value will be lower than if it were free from blemishes.

Exposure to Extreme Temperatures and Humidity

The formation of black spots on an amethyst is often caused by exposure to extreme temperatures and humidity. When an amethyst is exposed to these conditions, the crystals may start to crack, which can lead to the development of black spots. Although these black spots may not affect the appearance or value of the gemstone, they can be a sign that the amethyst has been damaged.

Exposure to Radiation

The black spots on some amethysts are caused by radiation exposure. When the stone is exposed to radiation, tiny fissures form in the surface and carbon particles can be deposited in these fractures. Over time, these particles can oxidize, turning the stone black.

Contaminated with Sulfur

Sulfur is a mineral that can be found in many different places. When it is contained in rocks and soil, it is usually in the form of sulfide minerals. In its pure form, sulfur is a yellow solid with a characteristic pungent odor. It is not often seen in nature, but when it is present, it can cause problems for gemstones.

If an amethyst is exposed to too much sulfur, it may develop black spots. These black spots are caused by the infiltration of sulfide minerals into the gemstone’s structure. While they do not always affect the appearance of the stone, they can reduce its value. If you are buying an amethyst, it is important to ask where it was mined.

Exposure to Nicotine or Other Toxins

Exposure to Nicotine can cause an amethyst may develop black spots. Amethysts that have been exposed to cigarette smoke, for example, may develop dark spots on their surface. These black spots are not a result of the stone’s color but rather a result of the toxins that have been absorbed by the stone.

While these black spots may not be aesthetically pleasing, they do not affect the durability or value of the stone. In most cases, they can be removed with a gentle cleaning solution.

Identification and Removal

Black spots on an amethyst can be identified and removed to maintain the appearance and value of the gemstone. Amethysts with black spots can often be found at lower prices, so it is important to spot these blemishes on the stone.

If the black spots are not removed, they can spread and affect the entire stone. There are several methods that can be used to remove black spots from an amethyst, including polishing, soaking, and using a light source.

  • Polishing is the most common method for removing black spots from an amethyst. The stone can be polished with a soft cloth or with a polishing agent specifically designed for gemstones.
  • Soaking is another common method for removing black spots from an amethyst. The stone can be soaked in water or in a special solution that is designed to remove blemishes from gemstones.

Prevention of Black Spots from Forming on Amethysts

One way to prevent black spots from forming on amethysts is to regularly clean the gemstone. This can be done by using a soft bristle toothbrush and some warm water. Another way to help keep the gemstone clean is to store it in a fabric-lined jewelry box.

Another thing that can be done to prevent black spots from appearing on amethysts is to avoid exposing them to harsh chemicals or extreme heat. If they must be cleaned using harsh chemicals, then they should be rinsed off with cold water immediately afterwards.


In conclusion, while the cause of black spots on amethysts is not fully understood, it is likely that a combination of factors including environment, temperature, and humidity are responsible. Amethyst with black spots is still considered to be a valuable gemstone, and these blemishes typically do not affect the stone’s appearance or value.