How I Turn Rough Opal Into Professionally Cut Gems
Most people only ever see opal once it’s polished and sparkling in jewellery, but every black opal, crystal opal or white opal starts life as a rough, dusty stone. As a professional opal cutter working with Australian opals here in the UK, I take rough opal and transform it into the finished gems you see in my black opal collection.
If you’ve ever searched for black opals UK, rough opal for sale UK, opal cutter or cutting opals, this is exactly how the process works from my side of the bench.
You might also enjoy some of my other blogs:
- What Is Opal Brightness?
- How to Avoid Fake Opals When Shopping Online in the UK
- How to Care for Your Opal Jewellery
Choosing the Right Rough Opal
I work mainly with Australian material from Lightning Ridge, Coober Pedy and Mintabie. When I’m selecting rough opal—whether it’s rough opal, crystal opal or white opal—I’m looking for:
- Colour: Bright, clean play‑of‑colour that holds up in different lighting.
- Pattern: Rolling flash, broad flash, harlequin and rare patterns.
- Yield: How much finished gem I can realistically cut from the rough.
At this stage I’m already imagining whether the stone will become a pendant, a ring, or something for a collector looking for investment‑grade black opal.
Reading the Rough: Finding the Colour Bar
Every opal cutter needs to “read” the rough. The precious colour usually sits in a colour bar, and my job is to find it without grinding through it. I slowly remove potch and sandstone until the bar reveals itself. This is where experience matters—one wrong move and the best colour is gone forever.
This is especially important with black opal, where the dark base tone is what makes the stone so rare and valuable.
Planning the Cut
Once I’ve found the colour bar, I plan the cut. I decide:
- Orientation: Which direction shows the strongest colour.
- Shape: Oval, freeform, teardrop or something unusual.
- Thickness: Enough to keep strength without losing brightness.
For crystal opal, I also consider how light passes through the stone—sometimes a thinner cut makes the colours glow beautifully.
Cutting the Opal
I use diamond tools designed for opal, which sits around 5.5–6.5 on the Mohs scale. I trim away waste material to create a pre‑form, constantly checking the stone under water and different lighting.
Every decision affects the final value, especially with rare material like boulder opal or opal fossils.
Shaping and Doming
A good opal cabochon needs a smooth, even dome. Too flat and the stone looks dull; too high and it becomes difficult to set. I shape the dome slowly, protecting the colour bar and keeping the stone balanced.
Polishing: Where the Opal Comes Alive
Polishing is my favourite part. I move through finer grits until the surface becomes glassy and the colours explode with brightness. This is the moment the stone reveals its true personality.
Because opal can be fragile, I polish with plenty of water and a very light touch. Overheating can crack a stone instantly.
Grading and Pricing the Finished Gem
Once polished, I grade the opal based on brightness, pattern, body tone, size and overall appeal. This is how I price the stones you see in my collections:
Why Professional Cutting Matters
A well‑cut opal can be worth many times more than a poorly cut one. My job is to respect the stone, protect the colour bar and bring out the best possible face for jewellery or collecting.
If you’re searching for an opal cutter near me, or you have rough opal you’d like professionally cut, feel free to reach out.