Complete Guide on How to Cut Obsidian

Obsidian is named after Obsius, the Roman explorer who discovered it in Ethiopia. It’s an igneous rock made primarily from silica, and it’s formed as the lava from erupting volcanoes cools off.   

It’s a form of glass and a close cousin to quartz. This gemstone usually comes in shades of black, depending on which types of impurities fuse with it as it forms inside super hot lava. The pure mahogany color is the finest variety and it’s a little hard to find. 

This rock is so beautiful that it’s often used in jewelry-making. And naturally, cutting, carving, and polishing gemstones require a thorough knowledge of their physical properties and crystal structure. Inexperienced hands could easily break a fine piece or miss a subtle defect that should be handled early on. 

If you’re a gemstone hobbyist, or you’ve taken up lapidary work recently, you might be wondering how to cut this stone without shattering or scratching it. In this article, we’ll show you how to cut obsidian in the best possible way. 

Related: How To Polish Obsidian By Hand

How to Cut Obsidian In 5 Easy Steps

Obsidian is made from silicon oxide (SiO2), but its crystals are much too irregular, so it’s not considered a mineral. 

It’s stronger than glass, and that’s why it was used to make knives or arrowheads in ancient times. It has a reflective surface that’s sometimes polished thoroughly to make obsidian mirrors. More often, it’s used in making jewelry, in addition to Feng-Shui decor.

Here’s how you can cut obsidian and prepare it for further processing.

Related: My Guide To The Best Lapidary Tools For Beginners

Step #1: Prepare Your Workspace

Safety, productivity, and creativity, are all highly dependent on the state of your workspace. Furnish your workshop or craft-corner in a manner that optimizes your activities. Also, it’s important to maintain safe and comfortable conditions. You’d be spending a lot of time there.  

Cutting machines are among the power tools that require caution and preparedness. Your workspace should have sufficient space for moving around safely, good ventilation, all the hand tools you might need, in addition to some basics. This includes:

  • A sturdy flat surface, preferably a workbench
  • Safety electric plugs with the right rating
  • Proper lighting
  • Safety equipment like goggles, a mask, an apron, and gloves
  • A water supply for keeping the sawblades wet 
  • Cutting, grinding, carving, and polishing tools
  • Manual or digital measuring devices 
  • A precision vise that can be clamped to the bench 

Step # 2: Make Sure to Follow Proper Safety Practices

Safety is always first. That’s why before starting anything at all, check the correct way to perform the various gemstone cutting processes. 

Among the important measures is wearing a mask. Cutting stones often releases tiny dust-like particles, and these are seriously nasty if they get into the lungs. 

Goggles are also necessary. That’s because flying shards from the stone, or from the cutting blade, aren’t that uncommon. In fact, this is a recurring incident while cutting any material from wood to metal to gemstones. 

Good ventilation, fire safety, and electric safety, should be ensured. Moreover, mechanical safety against heavy objects, tripping on cables, or bumping into obstacles should also be considered. 

Finally, ergonomics shouldn’t be taken lightly. Sitting or standing in the same position for a long time could be quite taxing to the body. Choosing a suitable chair and bench should keep you comfortable and your body free from unnecessary stress. 

Step #3: Choose a Suitable Cutting Device

Obsidian has a hardness of 5 Mohs, with one harder variety which is basalt glass, and it has a hardness of 6 Mohs. This moderate hardness places Obsidian in the same hardness level as apatite, and just below quartz and feldspar. 

Thus, to cut obsidian, you’d need to use a strong saw. Moreover, the blade needs to be sharp enough to avoid fracturing or shattering the stone. In fact, you’d often need to make clean and fine cuts. And the only way to achieve that is by using a sturdy saw.

Diamond Saw

A 6” diamond lapidary trim saw should be good for most applications, but if you feel that you only need to work on small pieces, then a 4” cutting machine would do just as well. 

Dremel Tool

You could also work with a Dremel tool. You might also want to include a suitable accessory set of diamond cutting-wheels. Sometimes the included accessories in the basic Dremel set aren’t suitable for the hardness of your stones, so it’s recommended to get an extra set.   

Industrial Cutting Machines

Besides the bench-top varieties, there are also industrial-size cutting machines. That is, if you plan on working with large slabs of obsidian, or if you have a large workload. These machines usually work with high-pressure water-jet technology, and some models are laser-powered. 

On the upside, these machines have a much higher precision than the bench-top saws, and they can cut thin slivers of this fragile stone. On the downside, they are far more expensive, they occupy a lot of space, and they need a bit more training to operate. 

Step #4: Measure Twice and Cut Once

Michael Angelo rightfully said, “Every block of stone has a statue inside it and it is the task of the sculptor to discover it.”. 

  • Visualize the final shape and size of the obsidian stone before starting the saw. 
  • Inspect it for flaws, cleavage, or impurities.
  • The orientation of the piece matters, so try a few positions. 
  • Obsidian is a valuable stone, so it’s best to get the most out of it.

Once you’ve done all the prep work, and measured everything at least twice, you can now confidently start cutting.     

Step #5: Carve, Polish, and Take Pride in Your Work

Cutting a stone is only a step in a longer process, but it’s a fundamental one. A correct cut would facilitate all the subsequent work you’re going to do. 

Finally, hold the polished gemstone in your hands, and take pride in your work. 

In Conclusion

Obsidian is believed to have a protective effect from negativity and unpleasant emotions. Wearing it, or placing it within your surroundings is said to be uplifting. 

Besides, its black color goes nicely with any outfit, and it also matches most precious metals. It’s versatile, beautiful, and easy to work with.

It’s not surprising then that this stone is getting more popular with lapidary enthusiasts.   

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