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Definitely not a peridot!

Nick_G

Shiny_Rock
Joined
Sep 7, 2018
Messages
197
I wonder if it's synthetic spinel? An RI of 1.71 would be a fair match for the lower end of the range.

Does it fluoresce in LWUV?
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
If you are measuring a refractive index 1.71 than it's not sapphire. Sapphire should be 1.76.

Have you confirmed that your refractometer is accurate? What brand is it? Do you have a polarizing filter on your refractometer? If so, have you checked for two readings for each orientation? You should be taking 4 orientations, with two readings at each one.
Thank you for the reply. I was going from memory - but I think it was 1.76. 1.81 was in my head because that is the terminal limit. We will test again in a few minutes. Yes, we used the polarized filter and took two readings at each orientation but I can’t recall if we did four or two orientations. We will repeat right now.

We connected the microscope to a laptop and gave significantly better images. After thorough cleaning, it looks as if the stone is painted. I will post those photos next. Then refractometer time.

The refractometer doesn’t have a brand name (it’s used and came from a lab). It says Geological refractometer on the box. Documentation says Gem Refractometer but it’s accurately identified peridot, blue sapphire, diamond and a few others so far. I’ll be back.
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
Refractometer readings at all 4 orientations are a little more than 1.75 and jump to 1.76.

The microscope pics are cool. They show what looks like a coating. Then striating in the surface only - they disappear as soon as we move in towards the stone interior - they look like brush strokes. Various other views included for your inner geek.

E8219289-9A7B-4888-B680-0FA043F358CC.jpeg E8219289-9A7B-4888-B680-0FA043F358CC.jpeg A5C1A88B-B44D-44AD-94D6-088B8E653AA6.jpeg 151D576D-5E66-4D1F-9FC3-D1987BC1DFA9.jpeg D45A6518-191A-44D6-B49E-68F42EEE66E1.jpeg C8CA8E1E-6C9D-483D-B31A-4F732049A73E.jpeg F4C17489-E1CD-4C8D-A2EF-53BF407BD330.jpeg 88E3070C-DB56-4011-96E9-E78A488BB6F6.jpeg C9EA48A9-AA26-41E2-B269-1222A9BF90C7.jpeg D270C4E9-AF1E-4A44-B3CF-62021002C03B.jpeg
 

2Neezers

Brilliant_Rock
Premium
Joined
Jan 8, 2014
Messages
1,479
This is interesting! Has the stone been cleaned? Could it be grimy film? I'd soak it overnight in dawn soap and give it a good hot water scrub in the morning if you haven't already.
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
This is interesting! Has the stone been cleaned? Could it be grimy film? I'd soak it overnight in dawn soap and give it a good hot water scrub in the morning if you haven't already.
It’s been cleaned, steamed, bathed in alcohol, and still it remains. It doesn’t seem to be dirt or a grimy film. The setting was fairly clean, too. We even tried a bit of gentle scraping. No change. DH might soak it overnight.
 

Daisys and Diamonds

Ideal_Rock
Joined
Apr 30, 2019
Messages
9,886
We are. A nice unstressful way to spend a few precious hours with DH. He’s so stressed keeping patients, staff and family all safe. Plus he’s happy to enable me. Speaking of which, I’m posting a new little addition to the gem box in another thread. It just arrived today.

That was a very good gift then .

Any ideas yet what kind of setting you might put this 'unperidot' ring into
Its done such a good job providing distraction and entertainment it surley deserves a future with you
 

Polyhex

Brilliant_Rock
Joined
Sep 18, 2003
Messages
550
It’s been cleaned, steamed, bathed in alcohol, and still it remains. It doesn’t seem to be dirt or a grimy film. The setting was fairly clean, too. We even tried a bit of gentle scraping. No change. DH might soak it overnight.

If you are OK with removing the coating (if it is a coating) then try soaking it in acetone.

This is fascinating. Is that a tiny culet on it in your photos? I love the unperidot!
 

LightBright

Brilliant_Rock
Premium
Joined
Mar 11, 2013
Messages
924
I’d like to know more about the coating. I’ve seen that opalescent film that doesn’t wash off on the pavilion of antique diamonds before. I don’t know what it is.
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
@LightBright we are curious, too. We cleaned is with acetone and 95% is gone, and the stone is still yellow. Lol. We are soaking it now, to see if we can remove the residual patches. The brush marks are gone as is the “AR” effect (anti reflective coating used in optic lenses). The performance outside is amazing. I’ll post pics of the first acetone cleaning and the second when it is done. We can see the polish marks on the facets, it no more brush marks.
 

Polyhex

Brilliant_Rock
Joined
Sep 18, 2003
Messages
550
@LightBright we are curious, too. We cleaned is with acetone and 95% is gone, and the stone is still yellow. Lol. We are soaking it now, to see if we can remove the residual patches. The brush marks are gone as is the “AR” effect (anti reflective coating used in optic lenses). The performance outside is amazing. I’ll post pics of the first acetone cleaning and the second when it is done. We can see the polish marks on the facets, it no more brush marks.

I bet it was flux residue from the ring being worked on with a torch in the past, ie for resizing. I missed the photos of the original ring, that is 100% an antique, 100 years old or more. If it's synthetic it is nevertheless very special, cut by hand by a master 100+ years ago.

Edit - adding, I agree with the earlier rationale it's probably synthetic because of the 10k setting BUT it's worth either you learning how to ID synthetic sapphire vs. natural with your tools, or taking it to be checked out. I have bought OEC and OMC natural diamonds set into basically the same Victorian setting. There was a great thread recently that went into depth on the most obvious ways to ID synthetic vs. natural sapphire. The age of this stone rules out sophisticated modern treatments.
 
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bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
These are pics of the cleaned stone. The faint lines seen “on” the facets are actually under the surface. All straight lines. With a loupe, I can see tiny hash mark looking inclusions in a few areas of the interior - not unlike those I saw in the lotus inclusion library. I wasn’t able to capture that under the microscope for photos, unfortunately.

T EEE6AF11-13F3-4854-9E56-7ED896F06E86.jpeg here are no curved lines, curved zones or curved anything else that we can see. Wondering what else we can do.

We took it to our local jewelry store today but it turns out we have more tools than they do for gem identification.
I tried the water immersion method, but could see more through the microscope.

Lol. We’re going to need a bigger boat! :geek:
 

Attachments

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
Doesn't this photo show curved striae? 934D7792-F3B5-4EEF-9F94-E1FA94C692E2.png

These were the early photos and there was something painted on the outside of the stone. We soaked and cleaned with acetone and they all came off. See the later photos - no more brush marks. It’s been suggested it might have been flux from a long ago service of setting or sizing.
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
@pokerface, I think I see what you mean. I have a lot to learn - In the top photo, it seemed to me the lines are straight and I don’t see a curve at all. I’d love to learn more - can you help me see the curve? I. The second photo - the curved light reflection (in blue) is the result of the round light it is reflecting. That photo was to show the change in the residue (as you can see, some still remains). Can you help me see the striae in that photo?

I’m grateful for any additional help in learning. I did use the lotus library to review their wonderful photos of inclusions and striae. It will be a challenge to use my home tools to view and capture the gem’s characteristics clearly - but I’m determined to try. =)2
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
It does look very similar to our vendor’s pics! DH contacted the seller of my stone and setting (not Etsy) and it turns out he’s from my hometown. He didn’t have much more info except that it was part of a local estate and he’s certain it’s a natural stone. He also thinks it’s a peridot, though lol. Of course, that in no way precludes a synthetic stone and as other posters have said, the whole setup points in that direction, too. Either way, not much was spent because it was just to go along with the tools for practice. I’m still having a blast. Even if synthetic, IRL it’s a very lively and pretty yellow stone (no hint of the greenish tint in his photos). I’m so grateful for the continued input. It’s the only way to learn!
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
So we improvised a polariscope. As we already knew from the refractometer, doubly refractive. I was hand holding the stone under the microscope, so it was difficult to get super clear shots, but they aren’t terrible. FB59147C-2142-48A4-941C-FBCE7E687F57.jpeg 9B6E0E48-2897-4C54-82F3-A4DF1FEA456A.jpeg 9B6E0E48-2897-4C54-82F3-A4DF1FEA456A.jpeg
 

Daisys and Diamonds

Ideal_Rock
Joined
Apr 30, 2019
Messages
9,886
So we improvised a polariscope. As we already knew from the refractometer, doubly refractive. I was hand holding the stone under the microscope, so it was difficult to get super clear shots, but they aren’t terrible. FB59147C-2142-48A4-941C-FBCE7E687F57.jpeg 9B6E0E48-2897-4C54-82F3-A4DF1FEA456A.jpeg 9B6E0E48-2897-4C54-82F3-A4DF1FEA456A.jpeg

I have no idea what im surposed to be seeing but i just love looking at the underside of that stone
 

bright&shiny

Shiny_Rock
Joined
May 11, 2009
Messages
486
Lol - I’m not exactly sure either, but the first shows figures that look like bubbles under the girdle. We couldn’t see them with the loupe, though.

The second and third photos are the same. I think it shows the same lines that are visible in the regular light photos. Possibly (probably) slightly curved striae.

It was very tricky. I was hand holding the stone, in regular tweezers (my hands are super tired now) and using lenses from sunglasses taped to the light box and microscope. and taking photos. It was a sight to see. Anyway, all in the service of learning.
 
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