Onyx - Color, Types, and Properties
Onyx
Onyx is a banded variety of chalcedony, which is a type of microcrystalline quartz. Onyx is characterized by its parallel bands of different colors. The most common color combination is black and white, but onyx can also be found in other colors, such as red, brown, and green.
![]() |
Onxy stone. Photo credit: UCL Geology Collections |
Agate and onyx are both varieties of layered chalcedony that differ only in the form of the bands: agate has curved chaotic bands and onyx has parallel bands. Its multi-layered structure is similar to that of agates. When the stone has a black base and a white upper layer, it's called onyx. When the base is brown, it is called sardonyx while carnelian-onyx has a red base.
Onyx comes through Latin (of the same spelling), from the Ancient Greek ὄνυξ, meaning "claw" or "fingernail". Onyx with flesh-colored and white bands can sometimes resemble a fingernail.
Onyx Types and Colors
Onyx isn’t an actual family of gemstones, rather a term used to describe layered stones that contain bands of black and white.
Black Onyx
The
most sought-after type, black onyx, exhibits deep black bands, often
with white or gray streaks. It is widely used in jewelry and ornamental
objects due to its elegant and timeless appeal.
White Onyx
This
variant showcases bands of white, often with a translucent appearance.
White onyx is cherished for its purity and is commonly used in carvings
and sculptures.
Green Onyx
Characterized
by captivating green bands, this type of onyx exudes a sense of
tranquility. It is popular in jewelry and decorative pieces.
Red Onyx
With
vibrant red bands, red onyx is a rare and luxurious variation. It is
frequently used in high-end jewelry and unique interior designs.
Sardonyx
Sardonyx
is a variety of onyx that exhibits bands of brownish-red (sard) and
white or black. It is highly prized for its distinctive appearance and
is frequently used in cameos and intaglios.
![]() |
Onxy agate with Quartz from Uruguay, at the Mineralogy Gallery in Paris. Photo: Camille Gévaudan |
Artificial treatments have been used since ancient times to produce both the black color in "black onyx" and the reds and yellows in sardonyx. Most "black onyx" on the market is artificially colored.
Onyx is the traditional birthstone for February. It is associated with relaxation and comfort.
Onyx is popular as a carving stone, since clever use of alternating bands of black and white can create a highly appealing carving.
Onyx is a gemstone found in various regions of the world including Greece, Yemen, Uruguay, Argentina, Australia, Brazil, Canada, China, Czech Republic, Germany, Pakistan, India, Indonesia, Madagascar, Latin America, the UK, and various states in the US.
Onyx is a variety or type of: Agate, which is a variety of Chalcedony, which is a variety of Quartz.
![]() |
Onyx from Brazil. Photo: James St. John |
Onyx Properties
Crystal System: Trigonal
Color: Various
Cleavage: no cleavage
Fracture: Onyx has a conchoidal fracture, which means that it breaks into smooth, curved surfaces that resemble the inside of a seashell.
Mohs scale hardness: 6.5–7
Luster: Vitreous, silky
Streak: White
Specific gravity: 2.55–2.70 g/cm³
![]() |
Natural Onxy. Photo credit: UCL Geology Collections |