Can You Tell The Difference Between Black Obsidian, Black Tourmaline and Onyx

There is something intensely alluring, magical, and mystical about black crystals and stones. Gazing at them is like looking into infinity. Whether raw or polished, they are excellent choices for beaded bracelets and a wide range of crystal jewellery pieces, adding sophistication to any occasion.

Black gemstones and crystals... can you tell the difference?

What features define Black Obsidian, Black Tourmaline, and Onyx, and how can you tell them apart?

It might be easier to recognize them in their raw form since they are strikingly different. But in a beaded bracelet, for example, is there a way to tell the difference? Is it possible to establish the authenticity of crystal in a piece of jewellery? 

Facts About Each Gem

You've probably seen and admired these gems, even if you weren't quite sure what you were looking at. Here are some facts about each of these three types of gemstones. 

Black Obsidian

A deep, reflective stone when polished, black obsidian is shiny, smooth, and hard. A popular choice for home décor and crystal jewellery, this elegant gemstone has its origins in the heart of a volcano. It is formed from lava that cools very quickly. 
  Closeup of Black Obsidian Crystal both smooth and raw examples...

Even though many people refer to black obsidian as a crystal, it is technically volcanic glass. However, its beauty makes it supremely popular for beaded bracelets and necklaces and many other jewellery pieces. 

Black Tourmaline

This eye-catching gem comes in many colours, including black, and has a distinctive crystal structure. It's made of long crystal columns in the shape of three-sided prisms. This alone makes tourmaline quite impressive, as it's classified as having a ditrigonal pyramidal shape that many are drawn to. 

An example of Black Tourmaline in it's raw state...

Its unique symmetry makes black tourmaline nothing short of exquisite. Iron gives this crystal its colour. Tourmaline describes a family of minerals with the same basic crystal structure. Many healers believe in its ability to clear spaces by soaking up negative energy. 


Like agate, black onyx has tell-tale layered parallel bands, and it's not uncommon to see white streaks running alongside each other in this exotic crystal. Throughout history, it's been a popular gemstone for intricate carvings as well as delicate crystal jewellery.

An example of Onxy in it's raw state - gemstone and crystal information

Ancient Romans used it as protection in battle, and midwives in England kept it nearby to help mothers during childbirth. A type of microcrystalline quartz, black onyx has an appearance that's been described as everything from marble to a smooth block of ice. 

What To Notice In Their Raw Form

These gems have specific characteristics you can look for to help you identify them in their raw state. Here is what you'll find upon closer inspection:

  • Black Obsidian: Glassy appearance, reflective, different shapes, similar to frozen liquid, smooth, typically jet black, lustrous 
  • Black Tourmaline: Prismatic, long columns, glassy black layers arranged side by side, inky black colour, ridged, grooved straight lines, straight formation layers, high brilliance, twinkles 
  • Onyx: Black with (sometimes) white bands, marble-like appearance, opaque or slightly transparent, layered, parallel bands, icy, smooth

You can own crystal jewellery, artwork, or home décor pieces that incorporate the raw form of these gemstones. And based on the above descriptions, it can be reasonably easy to tell the gems apart.

But when they're polished, these beautiful stones are refined and transformed, taking on a whole different look. 

Establishing Authenticity In Crystal Jewellery

If you are considering buying a beaded bracelet or necklace made from black stones, the beads will likely be highly polished. It's important, then, to know what to look for when trying to differentiate between onyx, tourmaline, and obsidian in their finished states. 

Polished Black Obsidian

When black obsidian has been worked for use in jewellery, you may notice the following:

  • Lightweight
  • Smooth 
  • Glassy
  • Deep black

Polished Black Tourmaline

Particularly in beaded bracelets, tourmaline that has been polished or tumbled often takes on the crystal brilliance of its raw form. You may see these traits:

  • More substantial weight
  • May have surface veins
  • Has natural variations
  • Glossy surface
  • Sparkly below the surface

Polished Black Onyx

This gemstone is also often used in beaded bracelets. You want to make sure to distinguish between onyx and tourmaline in particular. Here's what to look for in polished black onyx:

  • High polish
  • Possible white streaks parallel to each other
  • Slightly transparent
  • Heavier than obsidian

Ways To Protect Yourself When Buying Crystal Jewellery

We've covered what to look for in black tourmaline, onyx, and obsidian, explaining what each stone is and what it looks like in its raw form. 

We've also gone over how the polished versions of these stones may appear. These differentiations will help you determine whether that charming beaded bracelet you purchase is truly made from tourmaline, for example. Or if that necklace pendant is made from obsidian or onyx.

There are other ways to protect your purchase and establish authenticity in crystal jewellery. We recommend the following:

  • Buy only from trusted, reputable sources
  • Request a letter of authenticity
  • Have your jewellery inspected by a local expert
  • Make sure the company you buy from has a fair return policy
  • Familiarize yourself with the look of different crystals
  • When in doubt, ask

You may benefit from online searches to see what black gemstones look like in their raw and polished forms. 

You may also choose to go to your natural history museum, crystal shop, or local jeweller and ask to see examples of black tourmaline, obsidian, and onyx in crystal jewellery or in its raw form. 

Seeing these beautiful gems in person will help you know tangibly what different gemstones look like and how they feel to the touch. You'll see how they reflect light, which one's sparkle, which ones are shinier, which are translucent, and which are opaquer. 

You'll also feel the variation in weight. You may even detect the subtle vibrancy and energies associated with each type of crystal.

Knowledge is power. So when you're purchasing a jewellery item that speaks to you and brings out your unique attributes, you want to make sure you are getting what you expect. 

There are price differences between black tourmaline, onyx, and obsidian. By purchasing from a trusted source, you'll be paying the right amount for the right gemstone. 

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