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How to determine whether onyx is real or not?

Onyx is not a very expensive gem, but in demand, therefore it is often counterfeited, especially in the manufacture of jewelry. He is also ornamental stone: it is often replaced with cheaper analogues, for example, agate or marble. Today we will tell you how you can distinguish natural onyx from fake.

How to make a fake

Are applied two methods creating fake onyxes. The first is that agate or marble is painted and their structure is changed using different chemical reactions. Typically, such crystals are used in the production of jewelry. The second is artificial grow a mineral that consists of polymers similar in structure and color to real onyx. A fake created in this way, even looks different from the original, it looks more like plastic or frosted glass. Such stones are often used as ornamental and finishing materials.

How to distinguish natural onyx from a fake

There are some criteria, which will help you find out which onyx is real or fake.


In a natural gem veins inside visible at a depth of 3-4 cm, they are easy to see, you don’t need to look closely. The fake crystal has too much dense structurethat it is impossible to see anything beyond the polishing layer.

Color saturation

Fake onyx is no different stable brightness colors. The reagents that craftsmen introduce into its structure to give the required shade, do not tolerate direct sunlight, moisture, sweat and fat. The fake quickly loses its brightness of color, gradually turning back into marble, agate, or even a piece of plastic.

Product weight

You can tell whether onyx is natural or not by its weight.

The natural mineral is quite heavy, while the fake one is light. If the imitation is made of agate or plastic, it will weigh much less

If you are familiar with these materials, you will easily recognize what is in front of you.

Gem drawing

If the internal pattern of onyx is too blurry or, conversely, clear, as if painted, stripes, then it’s fake. The structure of the natural rock is unique, its lines can not be too correct, neat.

Stone price

Real onyx does not cost a lot of money, but penny jewelry with it cannot be sold. You should not believe sellers who shout about good discounts and promotions on such products: no one will sell a natural mineral at a price that is less than it cost price. Simple beads or bracelets made of onyx beads cost at least 1000 rubles. Small souvenirs made from this stone have a value 2500-5000 rubles.


Jewelry is very popular now, especially rings with attractive black onyx. But in fact, this does not occur in nature! It comes in different shades: from light milky to dark brown. But charcoal There is no.

If you see a piece of jewelry with black onyx, it means you have colored agate or chalcedony.

Moreover, a natural mineral never happens plain: It has a heterogeneous structure. For example, there is an Arabic dark type of gem that combines both black and white stripes. Real onyx is different from fake several characteristics. If in doubt, take it to a jeweler for inspection, but it is best to take care before purchasing by asking the seller certificate on the product.

Black Agate and Black Onyx. How to distinguish a fake and are there real stones in nature?

To distinguish a fake from a real stone, you need to be a high-level specialist with a good supply of theoretical and practical knowledge. But there are several methods that will help you avoid buying “glass”. About them below in the interview. In addition, you will learn how black agate fundamentally differs from black onyx and why the latter is rarely used by manufacturers as a raw material for finished products. The topic of today’s conversation: black agate and black onyx. We addressed this question to a well-known specialist in Ukraine, geologist Andrei Ivanovich Martyshin. A question. Everyone is looking for black agate, black onyx, a lot of people are interested in this stone: from collectors to jewelry lovers, when they find and prepare to purchase it, one question arises that we hear very often – is this a real stone? – Well, in fact, this is not one question, but many at once, and it will even be difficult to answer all this in one video, I think we will even make a series. But let’s start with the basics. The main mistake: black onyx and black agate – these names appear in many jewelry catalogs and in many price tags of jewelry stores, and they are often used inappropriately. Why? Since, according to the science of gemology, agate is a striped variety of an aggregate of chalcedony and other silicic acid minerals SiO2, and onyx is generally a very broad name for stones, from marble onyx, which we can find in caves, whoever was in the caves saw stalactites and stalagmites made of marble onyx, and to jewelry varieties of the mineral chalcedony quartz cristobalite and so on, derivatives of SiO2. And this is where all the confusion begins, so let’s take turns. This means that black agate exists in nature, it is in front of you, it is black-red-white (top left – approx.), and this is black-white-gray (middle left – approx.). Why do we say agate because it has several colors. If it was one color like this one (top right – approx.), it would just be black onyx. This is a jewelry name, it is not a mineralogical name. Here are just jewelry inserts made from black Brazilian agates (right in the middle – approx.), but they were originally of different colors, mostly pale gray tones, they are kept in aniline dyes, the natural color remains, but they are tinted and become more contrasting . The main raw material for production is this homogeneous Brazilian chalcedony (top right – approx.), aged in aniline or other dyes so that it is completely dyed black, because it is a natural stone formed during a volcanic eruption in southern Brazil around 300 million years ago in the Parana River basin, and this is actually black onyx, or you can call it black agate, but this is not quite the correct name. Regarding natural black onyxes. They exist, here is material also from Brazil (bottom left – approx.), here is material from Ukraine (bottom right – approx.), I personally found in the bed of the Latoritsa River in the area between Svalyava and Mukachevo, you yourself can walk along the bed and collect such black shiny stones, similar to these Indian ones (bottom left – approx.). And in India, the so-called onyx agate, this is this stone (a white stone on the bottom left – approx.), it is mainly black, white and red tones, this is a rock that was also formed during a volcanic eruption, there is a giant volcanic plateau in central India. Therefore, we will try to break all these concepts into separate ones and also make a more specific report on them. Now we have that black onyx and black agate are natural stone, with the exception of those manufacturers who fake it, replacing them with high-temperature glass, the so-called smalt. You can see for yourself by looking at the stone through a strong light. If it is black, opaque or brown, it will be a natural stone; if it shows some purple, green, pink, or other color, it will be a fake glass. Well, apparently these are the main provisions. – There is one question. If it is already tinted, that is, paint and aniline dyes already take some part in the process, the question arises: does it fade in the sun, how does it behave in the light, how stable is it. – Just like any fabric that also uses aniline dye. That is, it is hypoallergenic, it does not affect human health, which is why it is used for this. Well, let’s hope that’s exactly what those manufacturers did. There have never been any cases of black onyx burning out; in my fifty years of work, I have never heard of such a thing. And by the way, I also wanted to say. You see, this black onyx (bottom left – approx.) is natural, but manufacturers don’t want to work with it for a very simple reason – it always has some microcracks, stains, and so on, and the client also doesn’t want to receive a product with cracks and stains. That is why manufacturers use this chalcedony raw material (top right – approx.). – It seems clear, thank you. As you can understand from the interview, black onyx and black agate exist in nature, but you need to know several important nuances so as not to make a bad choice. Also, the naturalness of a stone does not always mean originality, and originality does not always mean aesthetic appeal. Therefore, it would be a good idea to set your priorities before purchasing. By the way, you can buy real black agate and black onyx on our website. Stones can come in different shapes and sizes, including cabochons and tumbling. If you need help selecting a mineral, just call the numbers listed on the website. We will provide comprehensive advice and help you make the right choice. Online store “Stones Market” – Your guide to the world of natural stones.

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