How can I tell if this opal is natural?

[nala]

Or not a doublet? It is being sold as a Boulder opal. The diamonds are old cuts

 

[JackTrick]

Do you have a photo of the opal from the side? and its back?

And do you happen to have an image of the opal before it was set?

 

[nala]

Do you have a photo of the opal from the side? and its back?

And do you happen to have an image of the opal before it was set?

No. The back side just looks flat, if i recall correctly

 

[Autumn in New England]

Oooo she sure is pretty. Yeah, it's fairly impossible to tell from this photo whether the stone is backed and/or capped. So the seller is saying solid boulder?

 

[nala]

Oooo she sure is pretty. Yeah, it's fairly impossible to tell from this photo whether the stone is backed and/or capped. So the seller is saying solid boulder?

What does backed or capped mean?
The seller is saying boulder and has it priced at 1600 but is having a half off sale.

 

[Autumn in New England]

What does backed or capped mean?
The seller is saying boulder and has it priced at 1600 but is having a half off sale.

So a natural opal would be one that is simply cut and polished. A doublet would be a cabochon that has a backing (usually potch, but can be any natural or manufactured material). A triplet is an opal that is backed and then capped with either crystal quartz or some other colorless material. Glue is used to adhere the backing and capping, so extra care has to be taken when wearing and cleaning the stone. I would ask the seller to be sure. Hope this helps!

 

[Bron357]

Boulder opal is solid opal on ironstone. If you can see the back of the gem then it’s relatively easy to tell.
A doublet is a thin piece of opal on a backing - usually potch. A doublet is usually flat topped or only very slightly domed. You need a side on view to see for certain.
A triplet is an even thinner sliver of opal onto a backing with a cap on top. This cap will be domed. Cheap opals it’s plastic, better quality triplets have crystal or even lab white sapphire. A triplet can be beautiful looking and in a ring with a lab sapphire top, very hard wearing, unlike natural opal which is low on MoHos.
This is a side view of a doublet.

 

[Starstruck8]

I'm not an opal expert but...

It doesn't jump out to me as obviously synthetic.

The usual way to spot a doublet is to look at the sides - the join between the stone and the backing is usually clean and straight. See @Bron357's example.

But here's the catch. With a bezelled stone this would require unsetting the stone, destroying the bezel in the process. The vendor probably won't want to do that. Maybe the vendor has a report or a picture of the unset stone? If not, it's an impasse.

Note also that doublets can be made with ironstone backing (not just potch, as Bron357 described). A seller trying to misrepresent such a doublet would have to describe it as boulder opal, because the ironstone back would be visible.

In your position, I wouldn't take the chance, unless the seller could give some positive evidence.

But that amounts to saying that I would never buy a bezelled opal, except from a trusted seller. So I'd miss out on a genuine solid opal from a legitimate seller... And what's an honest seller of such an opal to do? I don't know...

 

[dk168]

It's pretty and I like it.

However, I cannot tell if it is natural or not based on the photos in the original post, or whether it is a doublet or even a triplet.

DK

 

[nala]

I'm not an opal expert but...

It doesn't jump out to me as obviously synthetic.

The usual way to spot a doublet is to look at the sides - the join between the stone and the backing is usually clean and straight. See @Bron357's example.

But here's the catch. With a bezelled stone this would require unsetting the stone, destroying the bezel in the process. The vendor probably won't want to do that. Maybe the vendor has a report or a picture of the unset stone? If not, it's an impasse.

Note also that doublets can be made with ironstone backing (not just potch, as Bron357 described). A seller trying to misrepresent such a doublet would have to describe it as boulder opal, because the ironstone back would be visible.

In your position, I wouldn't take the chance, unless the seller could give some positive evidence.

But that amounts to saying that I would never buy a bezelled opal, except from a trusted seller. So I'd miss out on a genuine solid opal from a legitimate seller... And what's an honest seller of such an opal to do? I don't know...

Hi. An ironstone backing could still be a doublet, if I am understanding correctly?

 

[Starstruck8]

Hi. An ironstone backing could still be a doublet, if I am understanding correctly?

Yes. That's the problem. A natural boulder opal would (of course) have an ironstone back, but so would a doublet made with an ironstone backing. Unless you can see the edge, it's very hard to tell the difference.

A possible clue is that the colour layer in boulder opals is often thin and irregular, with 'dents' and bends. (You can see these by looking at the surface reflections.) So a high, smoothly curved dome would raise suspicions. But it's not conclusive either way.

 

[nala]

Zooming jn, I think I can see the stone is chipped. Can any of you see what layer it reveals?

 

[nala]

 

[nala]

 

[nala]

Yes. That's the problem. A natural boulder opal would (of course) have an ironstone back, but so would a doublet made with an ironstone backing. Unless you can see the edge, it's very hard to tell the difference.

A possible clue is that the colour layer in boulder opals is often thin and irregular, with 'dents' and bends. (You can see these by looking at the surface reflections.) So a high, smoothly curved dome would raise suspicions. But it's not conclusive either way.

Ok. Posted more pics!

 

[nala]

Boulder opal is solid opal on ironstone. If you can see the back of the gem then it’s relatively easy to tell.
A doublet is a thin piece of opal on a backing - usually potch. A doublet is usually flat topped or only very slightly domed. You need a side on view to see for certain.
A triplet is an even thinner sliver of opal onto a backing with a cap on top. This cap will be domed. Cheap opals it’s plastic, better quality triplets have crystal or even lab white sapphire. A triplet can be beautiful looking and in a ring with a lab sapphire top, very hard wearing, unlike natural opal which is low on MoHos.
This is a side view of a doublet.

Ty! Posted more pics!

 

[Starstruck8]

I'm confused!

The back is not what I expected to see:


A typical boulder opal back is red-brown-black, grainy and opaque. See this video from Black Opal Direct at about 0:8 to 0:10 seconds. The back of your stone looks more like darkish potch (if the grey colour in the picture is accurate).

That would make your stone a 'dark' opal (not a boulder opal), if it's solid. But: (a) The potch backs I've seen have been plain grey, sometimes with a bit of sand. I haven't seen them with coloured flecks, as in yours. So I just don't know whether this is a sign of anything amiss. (b) It could still be a doublet - without seeing the edge, it's hard to tell.

So it seems your stone could be a solid dark opal (which is good), or it could be a doublet (which is not so good). I'm leaning towards solid. But, as you can tell, I'm out of my depth, so I wouldn't want to mislead you. You need an actual expert. I'm sorry I can't be more help.

 

[JackTrick]

I'm confused!

The back is not what I expected to see:


A typical boulder opal back is red-brown-black, grainy and opaque. See this video from Black Opal Direct at about 0:8 to 0:10 seconds. The back of your stone looks more like darkish potch (if the grey colour in the picture is accurate).

That would make your stone a 'dark' opal (not a boulder opal), if it's solid. But: (a) The potch backs I've seen have been plain grey, sometimes with a bit of sand. I haven't seen them with coloured flecks, as in yours. So I just don't know whether this is a sign of anything amiss. (b) It could still be a doublet - without seeing the edge, it's hard to tell.

So it seems your stone could be a solid dark opal (which is good), or it could be a doublet (which is not so good). I'm leaning towards solid. But, as you can tell, I'm out of my depth, so I wouldn't want to mislead you. You need an actual expert. I'm sorry I can't be more help.

Color play on the back makes me think solid opal. It’s rarer to see on the back, but that’s good for the OP

 

[nala]

@Autumn in New England
Thoughts?

 

[nala]

Color play on the back makes me think solid opal. It’s rarer to see on the back, but that’s good for the OP

Does color play mean color shift? Bc I swear I keep seeing colors change!

 

[Starstruck8]

Does color play mean color shift? Bc I swear I keep seeing colors change!

Yes. Just like the colour play you see in the front of the opal, but in patches, embedded in potch. Colour play means that colours vary with the viewing angle and the direction of the lighting.

 

[Autumn in New England]

Color play on the back makes me think solid opal. It’s rarer to see on the back, but that’s good for the OP

This ^. My solid opal has color-play on the back as well. I've never seen a doublet like that. The back is usually a uniform black, gray, or brown, etc. I'd still need to examine it in person to be 100%, but I'd put my money on solid opal. And it's lovely!!

 

[nala]

Wow! I am so excited. I did purchase it and have 30 days exchange window. So far I am loving her! Ty all!

 

[Autumn in New England]

Wow! I am so excited. I did purchase it and have 30 days exchange window. So far I am loving her! Ty all!

Glad you're enjoying her! Give that undergallery a good wash so the diamonds really sparkle. I use dawn dish soap, warm (not hot) water, and a soft brush. Have fun!!

 

[fredflintstone]

A video showing how the colors and pattern changes from front to back is the best way to judge an Opal's authenticity online.

If the colors stay the same and there is no movement in pattern that most likely suggest a lab Opal.

But you did a good job with the pictures. I would say it is natural.

 

[Garry H (Cut Nut)]

A video showing how the colors and pattern changes from front to back is the best way to judge an Opal's authenticity online.

If the colors stay the same and there is no movement in pattern that most likely suggest a lab Opal.

But you did a good job with the pictures. I would say it is natural.

Seems like there are no more synthetic gemstones since synthetic diamonds got rebranded?

 

[nala]

Seems like there are no more synthetic gemstones since synthetic diamonds got rebranded?

Is this comment directed at my stone? Care to elaborate?

 

[Garry H (Cut Nut)]

Oops - sorry Nala - directed at Fred terminology

 

[fredflintstone]

Seems like there are no more synthetic gemstones since synthetic diamonds got rebranded?

Hi Garry:

A lab created stone is a lab created stone as far as I'm concerned or synthetic if you will.

I've seen your many posts on lab Diamonds on "JHJ." I have not commented because I'm not in the business of selling Diamonds. Never have been. They just don't concern me. But if someone calls a lab created Diamond a natural Diamond, I'd be the first one to say they're not and explain why.

To be honest I don't even know what lab created Diamonds have been "rebranded" as, as I just don't pay much attention to Diamonds in general.

Not putting them down, just not interested in them to the point of concern. They do make nice accent stones though and are beautiful. Just too much overkill. I'm numb to them.

 

[dk168]

The uneven surface finish suggest it is not a doublet or triplet to my untrained eyes.

DK