URGENT: Opal Experts Please Help!

[theredspinel]

Straight to the point. This is an *estate* ring I just got. It was sold as a solid black Australian opal. The gold is marked as 18k. The opal is huge 6.something cts.

I am certain it's a solid opal. It has no potch on the back and some colour play. Louped it. 5th opal piece I own so I have limited experience with opal.

I would say 2.5 brightness if I'm being stingy. 3 on the brightness scale if not. Outside in the sun it's about 4 brightness (my little triangle shaped semi black next to it is a 4.5/5 brightness).

Rubbish indoor pictures as I'm in a rush. The opal seems to be set with clear glue residue around it also and the vendor said they did notice that and it is somewhat normal to use jewellers glue for extra protection so it doesn't fall out.

I'm certain it's not Gilson, certain it's solid no doublet or triplet. Now I need to know is it treated Ethiopian (I don't think so the colour play doesn't seem right but I've never seen ethppian opal). When I loupe it I see what looks like loads of black long thin needles (as it'd be called in other CS). What does this mean?

Any opinions?

THANK YOU!

 

[Acinom]

Do not have the expertise to help you with your question. Just wanted to say your new ring is STUNNING.

 

[Bluegemz]

Not much help here, but that setting looks like some from an expensive artist/designer’s pieces which I’ve seen. Can’t think of the name...
My first impression of it is that it might be a natural black Ethiopian opal. Ofcouse, the black may also have been treated into the stone too.
It’s gorgeous! Love the yellow gold too!

 

[theredspinel]

Not much help here, but that setting looks like some from an expensive artist/designer’s pieces which I’ve seen. Can’t think of the name...
My first impression of it is that it might be a natural black Ethiopian opal. Ofcouse, the black may also have been treated into the stone too.
It’s gorgeous! Love the yellow gold too!

Bluegemz any idea if I can at home test for treatement (the soaking methods) without ruining the glue part?

 

[theredspinel]

Btw I trust the vendor absolutely, if this is treated it's a mistake on his part not genuinly missold. He was ready to send to GIA but I was impatient eek.

This ring was part of a huge lot they bought out from a wealthy European lady and about 90% of the other stuff from her has GIA certification.

 

[Bluegemz]

Btw I trust the vendor absolutely, if this is treated it's a mistake on his part not genuinly missold. He was ready to send to GIA but I was impatient eek.

This ring was part of a huge lot they bought out from a wealthy European lady and about 90% of the other stuff from her has GIA certification.

Ii looks high quality to me. And given the setting, I can see why glue was used, ( even though it’s not my favorite, I’ve seen plenty of examples of cabs which are glued if they are held in with prongs.) The proportions show that there is significant artistic refinement in the piece.
There was a post about methods for checking this, but I believe they are destructive. I’ll try to find it soon.

 

[Bluegemz]

I’m having trouble finding it....what I remember is that false blacks from Australia and Ethiopia are smoked, and I think maybe some from Ethiopia are irradiated too? In the case of fire opal, dye is sometimes added, and I think this has been done to some Ethiopian opals as well. A destructive test involves soaking in acetone, but then the dye comes out of the stone, so it’s destructive. Maybe @Seaglow can help?
Honestly, I think your best bet would be sending it to the GIA, unless you can love it not fully knowing. If not, peace of mind is worth ALOT.

 

[lambskin]

Would like to see more pictures in different light and lighter backgrounds.

 

[Bluegemz]

Here is a GIA article about black opal from Ethiopia...

https://www.gia.edu/gems-gemology/winter-2014-gemnews-new-deposit-black-opal-from-ethiopia

 

[jordyonbass]

I'm seeing a slight brownish tinge to the body colour which leads me to believe it could possibly be cooked matrix opal, most likely from Andamooka if it is Australian.

 

[Bluegemz]

I’m confused, I thought that chocolate, reddish brown tones could be found in Black Ethiopian also? The Gia article mentioned that .... @jordyonbass , do you know how common that is for either Australian and Ethiopian? Do you happen to know of any way to distinguish between the two by color play? I would love to learn more.

 

[theredspinel]

I'm seeing a slight brownish tinge to the body colour which leads me to believe it could possibly be cooked matrix opal, most likely from Andamooka if it is Australian.

There's no brownish tinge, it's very very dark grey with blue overtone. I'll dig out my scale from Justin and check what N its on. The pics are showing the opal a tad blacker then it is. Matrix opal still a possibility?

 

[theredspinel]

Here is a GIA article about black opal from Ethiopia...

https://www.gia.edu/gems-gemology/winter-2014-gemnews-new-deposit-black-opal-from-ethiopia

Thanks so much!

 

[theredspinel]

Ok some more pictures under my front room lights. Daylight pictures will have to be done tomorrow it's currently night time here. The purple is picked up mostly by the camera it's not as apparent in real life at all.

 

[Seaglow]

I’m having trouble finding it....what I remember is that false blacks from Australia and Ethiopia are smoked, and I think maybe some from Ethiopia are irradiated too? In the case of fire opal, dye is sometimes added, and I think this has been done to some Ethiopian opals as well. A destructive test involves soaking in acetone, but then the dye comes out of the stone, so it’s destructive. Maybe @Seaglow can help?
Honestly, I think your best bet would be sending it to the GIA, unless you can love it not fully knowing. If not, peace of mind is worth ALOT.

Sugar treatment usually has more of the pinfire or small specks look. Smoke treatment is more convincing. If you have a microscope, you can look for burn marks or carbon/smoke concentrations..

 

[peacechick]

I agree that the opal looks like a welo. Do you think it looks like MiriamS’s opal ring here? It looks very close to me:

Any Opal lovers out there? Show and Tell please.

 

[jordyonbass]

@Bluegemz I don't know about cooking Ethiopian Opal, but a type of matrix opal from Andamooka is commonly cooked and the treatment gives a brownish-black body tone to the Opal. As far as distinguishing between the two locations - it can be extremely difficult with lower grade material, however I find that high quality stones from Australia are very obvious. Especially Lightning Ridge.

@theredspinel if the body tone is grey-black then I would think it isn't cooked matrix, strange because my phone shows it . I wish we could see a video as that would give a lot more away about this stone!

 

[Bluegemz]

@Bluegemz I don't know about cooking Ethiopian Opal, but a type of matrix opal from Andamooka is commonly cooked and the treatment gives a brownish-black body tone to the Opal. As far as distinguishing between the two locations - it can be extremely difficult with lower grade material, however I find that high quality stones from Australia are very obvious. Especially Lightning Ridge.

@theredspinel if the body tone is grey-black then I would think it isn't cooked matrix, strange because my phone shows it . I wish we could see a video as that would give a lot more away about this stone!

Thank you for the information!

 

[arkieb1]

@Bluegemz I don't know about cooking Ethiopian Opal, but a type of matrix opal from Andamooka is commonly cooked and the treatment gives a brownish-black body tone to the Opal. As far as distinguishing between the two locations - it can be extremely difficult with lower grade material, however I find that high quality stones from Australia are very obvious. Especially Lightning Ridge.

@theredspinel if the body tone is grey-black then I would think it isn't cooked matrix, strange because my phone shows it . I wish we could see a video as that would give a lot more away about this stone!

I thought the same thing when I saw it and then I read the description and looked at the second lot of photos and it's possible it's just bad pictures compared to what you or I would take. Opals for people that don't generally photograph them are notoriously difficult to capture unless you know what lighting to use.

At this point I'd take it to a valuer or a lab because the pics aren't giving a clear indication of where it's from.

 

[theredspinel]

I thought the same thing when I saw it and then I read the description and looked at the second lot of photos and it's possible it's just bad pictures compared to what you or I would take. Opals for people that don't generally photograph them are notoriously difficult to capture unless you know what lighting to use.

At this point I'd take it to a valuer or a lab because the pics aren't giving a clear indication of where it's from.

Yep they are awful pictures!! I'm only using my phone and lighting is rubbish and... yes just crap pics.

If I was to do the soaking in water test, what should I expect to see? If it's ethopian it will be hydrophane and lose all colour play, then when it dries colour play will come back. Will it come back lighter??

If the opal goes cloudy what could this mean? Anything else at all I should look out for?

(I dont know if I will do the soaking in water test but just gathering all and any info).

 

[theredspinel]

According to GIA natural ethopian black opals were only discovered in 2013 (I think) and this ring is from the late 1990's so is it definetly impossible for this to be a natural ethopian?

 

[GliderPoss]

I’m no expert either but it’s very beautiful! I also see brown undertones in the pics but I know first hand these beauties are so difficult to photograph accurately!

If you suspect it’s solid then it would be worth it to send to GIA for testing.

 

[ChanterelleJ]

According to GIA natural ethopian black opals were only discovered in 2013 (I think) and this ring is from the late 1990's so is it definetly impossible for this to be a natural ethopian?

If the stone is original to the setting this is probably true. But who could guarantee that? I would ask for the ring to be sent to GIA. If it turns out to be Australian black opal you have peace of mind and a great investment piece

 

[Bron357]

My 5 cents is - I think it is an Australian Black Crystal opal. Not common but they do exist.
The test with Ethiopian opals is put them in water, being hydroplane the colours will disappear. Then once it dries out, hours maybe a day, the colour play returns.

 

[theredspinel]

Another question if anyone can answer please. I'm trying to figure out how much doubt I should have, the likelihood of it being treated and what it means and weigh that against the mighty hassle of sending it across the world to GIA.

This opal is for sure original to the setting, these prongs were made purely for this stone and I can see that. Even on the underside it's set in such a way that the setting would have to be damaged to take the opal out.

So we can safely say this opal is at the very least 20 years old.

What treatments were they doing to the ethopian opals 20 years ago? How stable would they have been (likely to last 20 years - as this opal clearly has)?

 

[jordyonbass]

@theredspinel smoked would be my answer to your question, I remember Justin from BOD showing a test for a different treatment where he soaked a questionable Ethiopian 'black opal' in high proof alcohol and a dye ran out of the stone. He also mentioned it's a very recent treatment so we can rule that out if your stone is circa 2000. I am not sure if the same alcohol soak can be done to test for smoke treatment though - I only play with natural Aussie solid stuff and soaking them in high proof alcohol is part of my cutting process

 

[theredspinel]

@theredspinel smoked would be my answer to your question, I remember Justin from BOD showing a test for a different treatment where he soaked a questionable Ethiopian 'black opal' in high proof alcohol and a dye ran out of the stone. He also mentioned it's a very recent treatment so we can rule that out if your stone is circa 2000. I am not sure if the same alcohol soak can be done to test for smoke treatment though - I only play with natural Aussie solid stuff and soaking them in high proof alcohol is part of my cutting process

Sorry didn't quite understand, so are you saying smoking was or wasn't done in the late 1990's?

 

[theredspinel]

Just had a thought, anyone know anything about Indonesian opal??

 

[jordyonbass]

Sorry didn't quite understand, so are you saying smoking was or wasn't done in the late 1990's?

I'm not 100% - but I think it was around in the late 90s. I'm going to do a bit more digging on this one for you to see what I can find out about smoked Welo and when the treatment was discovered

 

[Seaglow]

Just had a thought, anyone know anything about Indonesian opal??

If you mean the Indonesian blacks, they have a dark body color, usually jet black, and notorious for crazing!