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Difference Between Black Diamond and Onyx

Difference Between Black Diamond and Onyx

Before we decide to buy a gift for a dear friend or significant other, we need to consider several things, especially if we plan on purchasing a gemstone. Most precious stones have distinct characteristics, but some are remarkably similar in appearance.

For most individuals, it’s quite difficult to differentiate some gemstones if they look at them from a distance. One of the best examples of that would be comparing black diamonds and onyxes.

The article: “Difference between black diamond and onyx”, was formed so that no one will make a mistake when comparing them.

Why are some diamonds colored black? Are black diamonds transparent? Can the same be said for onyxes? How careful do we have to be when we handle them? Are onyxes worth more or less than black diamonds? Are they historically significant in any way?

What are their main similarities, differences, and many other topics regarding the article will be discussed below, so don’t be afraid to scroll down! You’ll certainly learn a thing or two!

A Quick Introduction

Although a vast majority of people know a thing or two about regular white diamonds – most of them aren’t quite familiar with black diamonds. Because of that, we need to learn how to differentiate the key features among them.

As the name implies, white diamonds are entirely or nearly transparent, depending on which precious stone we are talking about. Needless to say, nearly transparent diamonds have several impurities within them which ultimately classifies them as imperfect.

On the other hand, crystal clear diamonds retain their right to be called entirely transparent, due to the lack of any sort of impurity within them. If you decide to dedicate yourself to expanding your knowledge on this matter, you’ll quickly find that there’s a lot to consume about their differences!

But, we didn’t gather here today to debate about their differences, but rather, the differences between black diamonds and onyxes.

Coincidentally, black diamonds are quite similar to regular diamonds, as they are often found with the predisposition of being transparent. Now, depending on which one are we talking about, some possess tiny dark specks, while others can be entirely black.

In nature, experts on mining diamonds often find more black diamonds that have small dark specks, rather than completely black diamonds. That shouldn’t come as a surprise, as pitch-black diamonds are one of the rarest types found in the wild.

On the other side of the coin, we have onyxes, a microcrystalline variety of quartz that can be in various regions of the world. Some of the more popular locations are Argentina, Brazil, Greece, Uruguay, India, Pakistan, China, and many others.

With that out of the way, let’s take a short break and take a closer look at the main differences between black diamonds and onyxes.

General Appearance

If we were to look at these two stones from a distance, we wouldn’t notice any particular difference in their general appearance. But, as soon as we hold them in our hands separately, the contrast between them becomes apparent.

As we previously discussed, black diamonds usually have several integrated black impurities that are even visible to the naked eye, with some stones being entirely black.

On the other hand, as soon as you take a closer look at an onyx, the first thing that you’ll notice is its unique glazed ceramic enhanced with high gloss. In the hands of an expert, the high gloss can be polished even further.

The bread and butter of this particular topic is their capability to allow light to pass through. Black diamonds, regardless of how impure or black they might be, will always retain their predisposition of being transparent, allowing most of the light to pass through.

On the other hand, onyxes aren’t described as transparent, but rather, as translucent, which gives them the ability to attract and reflect light to a certain degree. The degree to which they can allow light to pass through is dependent on the thickness, color, and surface finish of the onyxes.

As such, when it comes to transparency, black diamonds largely outshine the onyxes, as they will always catch more light and allow them to pass through, regardless of how black they might be.

So, if you’re in the market for a transparent gemstone, the obvious choice is the black diamond.

On the other hand, people that are interested in having a polished glazed surface ceramic look with high gloss should aim for onyxes. We will leave you to debate that topic among yourselves, as general preferences and tastes shouldn’t be judged!


Just because they appear to be similar, their compositions are entirely different. Black diamonds are made of the carbon molecule, whereas onyxes are chalcedony quartzes formed from oxygen and silicon.

As their compositions suggest, the overall hardness between them is quite apparent. Diamonds are located at the very top of the list, with a grade of 10 on the Mohs hardness scale. Onyxes can only dream about reaching that state, as they come only as a 7 on the Mohs scale.

Most of us are quite familiar with how hard and durable diamonds are – it’s nearly impossible to damage, break or shatter them without the usage of tools made from other diamonds.

To work on them, professional diamond cutters require a set of tools specifically made to resist and penetrate the diamond. It’s quite difficult to obtain such tools, as they are only made for handling in laboratories, which most ordinary people don’t have access to.

On the other hand, altering the appearance of onyxes comes as a breeze, as we can simply use any tools or materials that are listed as 7 or higher on the Mohs scale. Even ordinary hammers can easily shatter onyxes, given that the swing was precise, hard, and swift.


Most people aren’t bothered with these pieces of information, but they are crucial to understanding if you’re in a market for gemstones. In most cases, leisurely wearing pieces of jewelry embedded with black diamonds won’t pose any specific problems, as they are more than capable of defending themselves from accidental mishandling.

Contrary to black diamonds, onyxes embedded in jewelry don’t have the luxury of being protected from any forms of mishandling, as they can and will get chipped rather easily, given the circumstance. Because of that, we need to educate ourselves before we decide to purchase an onyx or two, especially if we intend to wear them as pieces of jewelry!

Most people easily neglect the overall process of cleaning onyxes, as they believe that they are similar in durability and hardness. The gap between numbers 7 and 10 is usually quite small in real life, but when it comes to the Mohs scale, the difference is large.

Regardless of what color the diamond might be, it can be safely handled while cleaning with nearly all solutions, given that they aren’t dangerously corrosive.

Dipping your black diamonds in hot water mixed with soap or other solutions won’t cause them any harm, whereas onyxes require lots of care. Even ordinary cleaning solutions can prove troublesome if it touches an onyx, as most of them contain chemicals that can potentially damage the gemstone or, at the very least, dye them in a different color.

Because of that, we highly advise consulting with your jeweler before you decide to clean your onyxes on your own, as unfortunate accidents occur all the time.

Professional jewelers are educated on all sorts of gemstones and minerals. They know which solutions are safe to use when cleaning your precious stones. Keep your onyxes safe at all times by consulting with your jeweler.

Most of them offer professional cleaning services with safe tools and solutions, which can be quite handy for saving the overall value and market price of your precious stones.

Speaking of market price…

Market Value

All gemstones have their worth measured with several key elements. When it comes to diamonds (black diamonds aren’t exempt from this rule), determining their price tag comes from evaluating their cut grade, color, clarity, and carats, which are most commonly known as the 4 C’s of diamonds.

Coincidentally, the general value of onyxes can be measured with the same mechanism as diamonds, most notably by carats. An average market value for a single carat onyx can range between $1 and $200, depending on its appearance, cut grade, and color. The overall price is even influenced by the clarity of onyxes, as having fewer impurities will lead to a more expensive gemstone.

On the other hand, black diamonds outshine onyxes in this department as well and often have a price tag of up to $2000 per carat. Some black diamonds are even more expensive than that, depending on how transparent they are.

Related Read: How Much Is A 1 Carat Black Diamond Worth?

On top of that, the overall value difference between black diamonds and onyxes can further gap if we take a closer look at the smoothness of their surfaces, inclusions, natural color, and, most importantly, their porosity.

All diamonds, including black diamonds, usually don’t suffer from that condition, as they are always cut and polished to a degree where porosity is nonexistent.

Unfortunately, the same can’t be said for onyxes, as a large majority of them are porous. As such, porous onyxes are prone to suffer both chemical and physical damage, which can further their overall value.

Overall Popularity

Contrary to some beliefs, black diamonds were only recently discovered, more specifically in the middle of the 19th century. As such, they don’t have a long and rich history like average diamonds which were found in the 4th century BC.

In the early days, black diamonds were as desired as they are today, as it was believed that diamonds should be entirely transparent, with a small number or no impurities whatsoever.

People from the past grew accustomed to clear diamonds, as they represented a symbol of wealth and power. Most of them viewed black diamonds as impure gemstones that can’t be measured to regular white ones.

But, as time passed, the interest in black diamonds rose to a degree that most people today have zero difficulties admiring their black appearance with dark particles hidden within them.

On the other hand, onyxes boast a significantly longer and richer history, as they hold religious and cultural significance associated with ancient Romans and Persians. Most onyxes were used by various artists, as they used their skills to turn them into beads.

All things considered, the historical significance favors onyxes. But, black diamonds aren’t entirely exempt from this topic, as the overall popularity and interest in black diamonds rise by the day.

In Conclusion

As we slowly approach the final lap of this race, let’s review the key elements of the article “Difference between black diamond and onyx” – you might’ve missed something!

All diamonds, including black diamonds, have the ability to catch and release light, providing a spectacular shining effect. The same can’t be said to that extent for onyxes, as they are primarily translucent, with a glazed ceramic surface that has a high gloss.

Black diamonds are formed from carbon molecules, whereas onyxes are made from chalcedony quartzes formed from oxygen and silicon. As such, they are significantly less durable than black diamonds, which are rated as 10 on the Mohs scale.

Onyxes require lots of attention when handling them, especially when we need to clean them, as they are prone to surface damage and discoloration when put in contact with most solutions. When it comes to the market value, black diamonds are significantly more expensive than onyxes, which can be purchased for $1 to $200 per carat.

We are certain that you’ve learned a thing or two today. Be sure to stop by whenever you wish to learn more about gemstones!