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The word Sardonyx is derived from the Greek ‘sard’ meaning reddish brown, and onyx meaning veined gem. There is an ancient Greek myth behind the origin of the word Onyx or onux, the Greek word for fingernail. The legend says that Eros (Cupid) clipped the goddess Venus’ fingernails while she was sleeping and scattered them on the beaches of the Earth. Seeing what had transpired, the fates turned the fingernails to stone. These stones became the chalcedony stones that the Greeks called Onyx. Centuries later, the Romans applied the term to black and dark brown chalcedony.

Black Onyx was used in the memorial jewellery of Queen Victoria’s mourning period. The jewellery of this period was somber and reflected the monarch’s sadness, so this gemstone was in high demand and worked well in cameos to create stark pieces. In the Art Deco period, it was popular as a foil for rubies and clear quartz. The name was used by the Romans for a variety of stones including alabaster, chalcedony, and what is now known as onyx marble. Roman soldiers wore sardonyx talismans engraved with heroes such as Hercules or Mars, god of war. They believed that the stone would make the wearer as brave and daring as the figured carved on it. During the Renaissance, sardonyx was believed to bring eloquence upon the wearer and was regarded with great value by public speakers and orators.

Onyx is used as a heart, kidney, nerve, capillary, hair, eye and nail strengthener. It is said to help one sleep and helps to eliminate apathy, stress and neurological disorders.

This gemstone eliminates negative thinking, it is also believed to sharpen the wits of the wearer. Onyx is said to bring spiritual inspiration. It is a great assistance in holding emotions and passions under control and is used to help one change habits.

Sardonyx is the birthstone of Leo (Lion): July 23 – Aug 22.

Black Onyx is the anniversary gemstone for the 10th year of marriage.

This gemstone is a banded variety of chalcedony which is cryptocrystalline quartz. It is usually black, red or brown with white bands. The bands are typically straight, which separates it from banded agate, because the lines in banded agate are usually curved. Sardonyx is a type of Onyx with bands of Sard alternating with the stone’s white or black layers.

The layers in these stones range from translucent to opaque for sardonyx. The stones vary in colour too. They may be white or grey, ranging to many colourful varieties. Sardonyx stones usually contain flat-banded, white and brownish-red bands. It is a gemstone with alternating light and dark bands, which are coloured in brown, red, black, white and grey.

Sometimes people will sell greyish chalcedony or agate that has been dyed black or green to imitate. Calcite is also sold as this stone but discerning the two is actually quite easy because onyx is very hard, but something as soft as a fingernail can scratch Calcite. Also, some marble has been called onyx, but is much softer and subject to damage from acids. Black and coloured varieties are always dyed. It is easily dyed, so beware of the more ‘unnatural’ looking colours, such as bright blue, etc. This stone with red and white bands is sometimes referred to as ‘Sardonyx’ and it is the black variety of agate. However some parts are more or less translucent. This is why it is often heated to accentuate the colour.

The chief localities are India and South America.

It is usually cut into cabochon, or into beads, and is also used for intaglios and cameos. Some is natural but much is produced by the staining of agate. It is often used as a backdrop in jewellery and is also used as cabochons and as a building material. It is a rich-looking, affordable gemstone. It is often mixed with pearls to create elegant jewellery. Treated agate is often sold as Black Onyx.

It may chip or scratch rather easily, so store carefully and never allow two specimens to touch each other, so consideration is needed if you are thinking of including it into your engagement ring.