The onyx has been a highly revered gemstone for hundreds of years. This intriguing gem is a variety of layered chalcedony, which is a type of quartz. An onyx typically has a black base and a white upper layer, however the parallel bands present in between come in many color variations, including brown, white and grey. Sardonyx, a type of onyx, features a deep reddish-brown hue with white bands. In the jewelry industry, solid or dark colored onyx stones with light banding are quite sought after. Black onyx, the most popular variety, is usually a grey chalcedony that is treated to transform its hue. An original black onyx is very rarely found.

According to legends, onyx is believed to have come from Venus – the goddess of love. Several stories suggest that one day while Venus was asleep, Cupid clipped her divine fingernails with his arrow and left them scattered on the sand. To ensure no part of a heavenly body perishes, the gods turned those clippings into stones. While fingernails are not normally associated with the color black, the Greeks used the term “onyx” to describe all colors of chalcedony, from dark brown and black to fingernail-white. Later, the Romans restricted the usage of this term to only the black and dark brown colors of chalcedony.

The onyx is mined in many countries across the world, but U.S. and Brazil are the dominant producers. Other notable sources include Madagascar, Yemen, Pakistan and Uruguay.


The onyx is believed to provide protection and was often worn as a talisman. It is considered to promote emotional well-being by absorbing negative energies and relieving mental stress.

Persians and Indians believed that wearing an onyx would protect them from evil. Romans carried amulets of sardonyx engraved with the image of Mars, the god of war, with the belief that it would bestow them with the courage to fight battles. People in the Middle East are said to use onyx as a “worry stone”, which is supposed to be rubbed between fingers. This process is meant to help overcome conflicting and disturbing emotions.

Hardness & Strength

This gemstone is moderately hard and is suitable for most types of jewelry. Mohs scale of mineral hardness has given it a rating of 6.5 to 7, which makes it relatively durable. It is also resilient enough to deal with jewelry cuts that are normally utilized on harder gemstones, such as topaz or diamonds. Onyx has the malleability required to be cut into almost any shape. Its smooth, wax-like structure makes it apt for a variety of designs.


Since ancient times, onyx has been dyed to improve the depth of color, and especially to achieve the much-desired black hue. The treatment usually involves soaking chalcedony in a sugar solution, which penetrates the stone through the fractures present on the surface. It is then treated with hydrochloric or sulfuric acid, which helps carbonize the sugar deposited in the top layers of the stone. In addition to dyeing, onyx is also heat treated to enhance color or eliminate undesirable hues. These techniques are used extensively even today and are known to produce permanent results.


This alluring gemstone has been popular for several centuries, especially among the Greeks and Romans, and continues to fascinate even today. The value of an onyx is influenced by the factors mentioned below.


An onyx is either slightly translucent or fully opaque. In its most common form, this gemstone has a black base with a white upper layer. Some of its variants contain bands of different hues in between these two basic layers. As mentioned earlier, Sardonyx features a brown base layer with color bands in shades of red. Cornelia onyx has a red base, while the thin upper layer of a niccolo onyx makes the black base layer appear blue or grey. Onyx is also found in single colors with no color banding, with black being the most coveted and rare form of this gemstone.


This impressive gem is usually free from inclusions. A good quality onyx stone should ideally have a well-polished and reflective surface. Cracks or scratches on its surface can considerably bring down the price and quality.


Onyx can be cut into all standard shapes, such as rounds, squares, oval, trillion and marquise. Due to the presence of gorgeous bands of colors, an onyx is frequently carved into cameos, which beautifully enhances this distinctive feature of the stone. The onyx is also faceted and shaped into glossy cabochons.

It’s important to remember that the price of onyx jewelry is often dependent on the design and not on the gemstone itself, which is comparatively affordable. While larger pieces of this gemstone will cost more, the value will still be primarily influenced by the setting and design.

Care Instructions

Though a fairly durable gemstone, proper care is required to keep the beauty of the onyx intact and to also ensure longevity. Here are a few tips that will help maintain your onyx jewelry:

  • Keep aside your onyx jewelry when engaging in vigorous activities, like sports, exercise and cleaning so as to avoid scratches and dents.
  • Store this gemstone separately and not with other jewelry pieces.
  • You can use a mild soap water solution and a soft bristle brush to clean your onyx jewelry.
  • A moist cloth is also a good option to clean away any dirt accumulated on this gemstone.
  • Do not use ultrasonic cleaners or any chemicals as it may result in discoloration of the stone.
  • Use a fabric lined box or a soft cloth to store your onyx jewelry.