What Color is Onyx?

Black gemstones can make elegant jewelry, and black onyx has become very popular in part because there are relatively few gemstones that occur in black. Onyx is the most common and least expensive of all black gemstones, however onyx isn’t exactly black…let’s learn more about onyx and the different colors we can find it in. 

What Color is Natural Onyx? 

Onyx is a variety of stone that comes from chalcedony, a silicate mineral made mostly of calcite (similar to marble and granite). Onyx is naturally formed in caves around the world when water drips and evaporates from stalagmites and stalactites leaving behind traces of minerals in intricate parallel bands of varying colors. Agate and onyx are formed in the same way and look similar, but agate has curved bands that occur during formation which differentiates it from onyx though both are banded varieties of chalcedony. 

Depending on the color, onyx is classified into different types, the most common being Arabic Onyx which has a black base and a white upper layer. Sardonyx Onyx has a brown base with color bands in shades of red or yellow, while Cornelian Onyx has a red base with red and white bands. Niccolo Onyx has a thin white upper layer which can appear blue or grey against the black base color.

There are certain onyx varieties where the stone has a single color and no color banding. Black Onyx is the most popular variety in this category, but a solid black onyx or one with black layers thick enough to cut into a solid colored stone are very rarely found in nature. Most onyx is dyed to make its color uniform and heat treated to bring out its color intensity. These enhancements are common industry standards and do not impact the value or durability of the stone. 

Is Onyx a Good Gemstone for Jewelry? 

During the 1800’s onyx was popular in mourning jewelry; although onyx and the color black still carry funereal associations, jewelry styles since Victorian times have utilized onyx’s dark and opaque appearance to complement transparent colored gems including diamonds in a variety of pieces. The stark appearance and vitreous polish luster of onyxes make them center stones in their own right, and despite onyx’s opacity, gem cutters will often facet this stone because the flat surfaces can show a remarkable sheen. 

Black gemstones are eye-catching and uncommon and because of its neutral color, will go with any outfit. Some non-conventional couples are opting for black engagement rings, and onyx makes a great choice as it’s affordable, beautiful and similar to a black diamond although not as durable and shiny. Set onyx in yellow or rose gold for a vintage look and a strong contrast, or paired with white metals and accent diamonds, onyx has a modern and trendy look. Protective settings like the bezel and channel are fabulous choices for the black onyx.

Similar to other stones in the chalcedony family, Onyx has a plain, smooth, and waxy lustre with a rating of 6.5 to 7 on the Mohs scale, which means it isn’t extremely tough like a ruby, but it isn’t delicate either. You can definitely wear this gem, provided you take good care of it. You’ll want to store this stone in a velvet lined case away from other accessories to prevent scratches and make sure not expose it to harsh chemicals present in cleaners, sanitizers, cosmetics, perfumes, etc.  

With its striking beauty and mysterious charm onyx continues to be used in many types of jewelry. We can help you create a custom piece of jewelry with onyx or any other stone your heart desires. Give us a call at 303-385-8449 or click here to schedule an appointment.