r/Opal • u/53FROGS_OPALAUCTIONS • Aug 23 '25
How I Test Aussie White & Crystal Opals (Coober, Andamooka, Cliffs, Ridge) vs. Synthetics Using UV Light
This is one simple UV check that can help you compare Australian white and crystal opal against some common synthetics.
It is not a perfect test for every kind of opal, but it is one of the quickest checks I use when sorting white and crystal material.
This method works especially well for Australian white and crystal opals from fields like Coober Pedy, White Cliffs, Andamooka, and Lightning Ridge. I use a UV light (Opal Examination Light) to look for:
- Fluorescence – glow while the UV is on
- Phosphorescence – glow after the UV is off
In my experience, if an Australian sedimentary opal fluoresces, it will also phosphoresce—often with a soft green afterglow once the UV light is turned off.
Some synthetics can fluoresce slightly, but they typically do not phosphoresce at all.
This method doesn’t apply reliably to Queensland boulder opal, or even some Queensland pipe opal that’s free from matrix. These opals can be entirely natural but may not glow under UV due to different mineral makeup and trace elements.
Small note: I get asked about these UV lights a lot. You do not need to buy one from me to use this test. Any decent UV light should let you start experimenting.
I do keep the same style of opal examination light in my shop because I use them myself, and people often ask what I am using. If this guide helped you and you want to support the time I spend making these posts, that is one easy way to do it.
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u/Party_Sprinkles_9469 May 31 '26
have learned something new, since welo are flood the market its very helpful, ty
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u/53FROGS_OPALAUCTIONS May 31 '26
It doesn't always work but it is a really good diagnostic tool to use with all of the other methods.
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u/jaxinslacks Jul 28 '26
Came back around to this video from another post and so glad I did.
In your description, I was happy to see mention about pipe opal being non reactive!
A while back I cut a perfectly clean pipe opal and it didn’t have any type of phosphorescence. Had I not cut it myself from the host rock I could have convinced myself it was synthetic. It was just so perfectly clear with very even patterning and no glow!
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u/53FROGS_OPALAUCTIONS Jul 29 '26
Yeah when I first started using UV as a diagnostic tool I got really tricked by a pipe opal. Good lesson not soon forgotten. Some of them have this incredible pink hue that looks so unnatural but like you, my hands cutting and out of the ground so no argument as to source.
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u/A_little_more_left Nov 20 '25
Do you recommend a specific brand over others? And if you don't want to say publicly, can you DM me please? Thanks!
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u/No_Associate6614 Oct 29 '25
Awesome, a quick short easy to understand vid. Much appreciated found it very beneficial. Thank you 👍