All About Black Onyx: Types, Colors, Description, Origins & Details

Black: the color of style, drama and timeless class. Is there anybody who doesn’t just love wearing black jewelry?

Can you resist the lustrous beauty of Black Onyx? Nothing works like a black onyx when you want to make an evident yet graceful fashion statement! Having mentioned the beauty of Black onyx, don’t you feel the need to known this December birthstone better? We’re sure you do since our Black Onyx education guide is here to address all the basic knowledge revolving around black onyx right from its engrossing history and beliefs to the famous 4 C’s and properties for you to make the right choice while setting out to buy black onyx jewelry. Since we all have a special place for this semi-precious gemstone in our jewelry boxes, let’s get ourselves more informed:

Properties of Black Onyx

Having a hardness of 6-7 on Moh’s scale, Black onyx does require proper care when looking to wear on a regular basis.

This black variety of onyx is known to belong to the microcrystalline quartz family of mineral, also known as chalcedony and is known to be found in a trigonal like crystal pattern.

What makes it all the more alluring! Black onyx is known to possess a vitreous luster, or a glass like luster, with a refractive index of 2.58-2.64.

Origin & History

Let’s set the stage by exploring the fun history behind the emergence of this December birthstone with our black onyx education guide. Well, this black beauty has pretty divine origin. While black onyx is abundantly found today, it has a history dating way back to the time when goddess Venus was sleeping on the banks of indus river when her loving son Cupid chopped her nails just by his arrows. Interestingly, her fingernail fell into this serene river and since it had a divine origin, to stop it from vanishing it was turned into a black stone or some even suggest that after touching the bottom of the river, it automatically got metamorphosed into an Onyx. Pretty interesting and miraculous, right? In fact, the name onyx itself meaning fingernail in Greek. The craze for black onyx has always been on the rise with romans not only inlaying it in their seals but also believing it to work as protective gem for soldiers.

Where is Black Onyx found?

Having talked about its intense history, let’s see where this gorgeous black beauty comes from presently. Well, with USA and Brazil being its leading producers, it is also mined in Greece, Yemen, China, Germany, UK, Argentina, Uruguay, Madagascar, Australia and Pakistan. It is though considered to be pretty rare, specially the black variety. Talking about its specific formation, black onyx is sometimes considered synonymous to chalcedony. Interestingly, black onyx is formed under groundwater that carry calcite along with it. When it comes out in the form of spring water, these crystallize to form calcite crystals and minerals begin to settle out. Black onyx itself is known to be a pretty rare variety of chalcedony, a micro crystalline quartz.

Black Onyx versus Black Diamond

Black Onyx

First things first, talking about the appearance of black onyx, it tends to be quite opaque along with a glossy texture. The black color of this onyx is all thanks to it belonging to the chalcedony quartz, being composed of silicon dioxide. Also, it tends to be less expensive since it is more abundantly found.

Black Diamond

Interestingly, black diamond absorbs more light and is known to be clear without any transparency. Carbon is the element that black diamond is composed of. Also, since it is comparatively rare to find, it tends to be on the pricey side.

Black Onyx Quality and Price Filters

Nothing is more important while buying your precious black onyx jewelry than being well versed with its primary determinants of quality, i.e., the 4 Cs: cut, color, clarity and carat weight. These individually and together determine the value of your gemstone. Let’s take a look with our black onyx buying guide:

Onyxes occur in nature in banded colors but Black Onyx is the most common as well as the most famous variety of Onyx. In most of the cases, they are usually dyed to obtain the color. Unlike all the other colored gemstones, color is more determining factor than the inclusions in the gemstone. The most sought after color in black onyx is intense black with absolutely no color bands.

Usually Black Onyx contain little to no impurities producing high clarity in these gemstones. Onyxes can have shiny to dull luster with the gemstone being opaque. However, when setting out to buy a black onyx, choose the one with smooth surface with minimum to no cracks or inclusions.

The weight of black onyx is measured in terms of Carat Weight and unlike so many other gemstone, a carat weight does not have a dramatic effect on its price. The size of the gemstone is the primary determinant of its weight.

Black Onyxes are often cut into smooth glossy cabochons or else faceted to maximize the luster. Round and oval are the most common cuts for black onyxes since these cuts enhance the luster. They can be cut into many shapes such as trillion, cushion, pear, asscher and heart, etc.

Advanced Black Onyx

Want some more? Looking for other factors that determine the quality and value of this December birthstone? Take a glance with our black onyx guide:

The measurements of the onyx determines once again how well it sparkles and how well the facets can show off the color and clarity of the onyx. A well proportioned onyx of the same size, may look better than the one that is larger but has less than ideal measurements.

Black Onyx polish is how well the facets are polished and how smooth and even the surfaces are. If there is roughness, unevenness or remnants of the rough Black Onyx, the Onyx gets a lower quality.

In case of Black Onyx, when the gemstone is subjected to Ultraviolet Light the fluorescence imparted by the gemstone varies according to the bands present in the onyx and fluoresce partly strong yellow and blue-white.

Benefits of Black Onyx

From Cleopatra to fashion enthusiasts today wearing it proudly, this black beauty has come a long way. And of course comes with it, some common beliefs associated with it. That’s the fun part of wearing a gemstone. The rich history and astrological beliefs associated with it get us all the more excited to wear it:

Physical Healing

Having ties with root chakra, black onyx blesses the wearer with great physical strength, helping him overcome any issues related to bone marrow, bladder issue, menstrual problems, teeth problems, kidney problems, tissue structure along with teeth and eye sight issues.

Emotional Healing

Just like its bold black color, black onyx blesses the wearer with great mental strength, self confidence and a fearless attitude towards life. It helps you stay away from negative thoughts, depression and anxiety. All in all, it radiates positivity and happiness in the life of the wearer.

Other Benefits

Apart from that, it also helps in materialistic aspects of your life by blessing you with good fortune, wealth and prosperity. It also symbolize love and friendship and thus strengthens your relationship.


How is an Black Onyx formed?

The formation of Black Onyx takes place by the deposition of silica in gas cavities in lava, the result of which is the distinctive bands or stripes observed in the gemstone. The formation gives rise to different shades such as red, orange and brown.

What is difference between lab grown and natural Black Onyxes?

Like most of the gemstones, there is an option to choose between natural and lab-created black onyxes. One must not confuse “lab grown” with the “fake”. While synthetic is a replica the lab grown is developed in a controlled lab environment.

Yellow Sapphires whether natural or lab grown are made from the same base elements and hence are indistinguishable by hardness and physical properties.

Where do Black Onyxes come from?

Onyx are found at scattered locations all over the world such as Uruguay, bordering regions of Brazil, Afghanistan, India, Madagascar, Peru and the US. Also, California and Mexico remained a major source for onyxes.

How to take care of Black Onyx Jewelry?

Black Onyx Jewelry is quite easy to clean due to their hardness and durability. However, a few things must be kept in mind like avoiding contact of the gemstone with make-up, harsh chemicals, abrasives.

While cleaning the jewelry make use of lukewarm water and mild cleaning detergent. Soft toothbrush can be used to clean the underside of the Black Onyx.

Also, the jewelry must be individually kept to avoid contact with other jewelry to avoid unnecessary scratches.

What is a Black Onyx certification?

The most common Black Onyx Certifications includes from GIA, IGS and HRD labs. It is usually a document you receive on the behalf of the aforementioned 3rd party labs which describes an Black Onyx in all of its characteristics.

Can black onyx be worn everyday?

Yellow Sapphire, a semi-precious Having a hardness rating of 7 out of 10 on Moh’s scale which is slightly on the higher side, black onyx can withstand the wear and tear of regular use. Thus, you can wear this gemstone on a regular basis with proper care., is known to be the birthstone of September.

Is onyx treated?

Yes, a heat treated black onyx does exist and that too quite abundantly. The craze for this black variety of onyx has been on such a rise that it was to be created through artificial means. Since a natural black onyx is quite rare to find, chalcedony is treated by soaking in a sugar solution along with hydrochloric and sulfuric acid to obtain the lustrous black color.

Can black onyx go in sun?

Absolutely yes! Since it is intensely dark in color, it doesn’t fade out when exposed to direct sunlight, unlike some other gemstones.


Bold, bright and beautiful! That’s black onyx for you. The fashion appeal of this December birthstone is something we’re all a fan of. But don’t you agree knowing this black beauty better would only help us make a better decision while setting out to buy it? Pretty fun too, isn’t it? We sure think that we should be a little better education with the gemstone we all so fondly adorn. And to facilitate you with just that, we’re here with our black onyx education guide covering right from the history and beliefs to the 4 Cs and properties. All in all, an amalgamation of it all. Wonder no more how to buy black onyx jewelry! That being said, here we sign off wishing you all the luck in selecting your favorite black onyx jewelry. We’re sure it’d be just as pretty as you since you’re much more familiar with your gemstone now.