Posted on Leave a comment

950 carats of seam opal goodness!

Big, bold and a little unassuming — one thing is for certain, we’re going to need to bring out the heavy grit wheel to work on this monster gem.
Weighing in at a colossal 950 carats, we’ll need to clear the schedule to work on this piece of rough opal.

Tips & Tricks

Unearthed in the Grawin Feild in Lighntning Ridge, otherwise known as ‘seam opal country’, pieces like this one can be rare due to the size the cavity must be to create it.
Slides, fissures and cracks underground caused by movements in the earth for over hundreds of milliions of years create these cavities which fill up with silica spheres to form solid opal — imagine how large the cavity must have been where this one was formed!
On one side of the rough there is a natural cleavage, which tells me there was a join between that and another piece of opal, which I never got to see.

After my initial review of the piece, I knew I would need to cut it down a little on the slicer as the color bar did taper off just before one of the edges.
Tip – If you want to keep your slicer blade in the best condition, make sure you use a lot of water when slicing and be patient (unlike me) when guiding the stone through. This will keep the diamonds on the blade intact and it will last a lot longer.

Larger pieces of rough can be challanging, stressful & risky — it only takes one piece of potch or sand in the middle to ruin it.
Once I have started to really work this piece I could see a great pattern starting to emerge.
Although the pattern is coming through, the color bar is starting to thin — this is because the gem is not cleaning up like I thought it would.
So much pressure not to lose that color…eeeek!
Thankfully, the inclusions cleared away and we were left with a lovely large pinfire & flagstone pattern dark opal.

The Final Specimen

This humble piece of Lightning Ridge Seam Opal started at 950 carats and finished off as a nice 376ct freeform specimen.
At a buying cost of $4000 I would price the final piece at $6000 — you can find it here.
We hope you enjoyed watching something a little different as much as I enjoyed cutting and sharing it with you!

Want to watch another large speciman video?
Check out my Map of Australia that didn’t quite work out here.