Featured Screw back earrings, please help identify blue stone

Hi,
The below earrings are 9 cart gold with screw backs, but I can’t identify the stone. It looks like mother of pearl, but blue, the shine moves with light. Can it be foiled glass? I have purchased them because of the screw backs, the stone has to be special, I think.
Also, I want to give them a good wash, will I damage them?
Thank you.
@Ownedbybear @KSW @Bronwen @PepperAnna

 

Screw-threaded backs anyway. Screwbacks are generally non-pierced earrings. Apatite comes in that color but it's soft. The only thing I know that would match the color is glass-topped "glacier pearl", aka paua shell.

 

I’d think glass and I’d be very wary of washing in case they’re foil backed.

 

Yes, they look like foil glass, the seller sold them as sapphire (tested)… Why would they have a screwbacks? Is foil glass expensive?
Thank you.

 

Paua abalone can look like this. I can see other possibilities that better photos might confirm or negate. Sapphire is not among them.

 

Foiled glass is essentially a rhinestone. The screw threads are a leftover from the old days . A few good earrings are still made this way, but in the old days even a few costume earrings had them. The screw threads were for using with a threaded earring back; they're quite secure. Also a pain to take off if your fingers don't work well.

 

Thank you. I will take some better photos tomorrow, today was a rainy day in London.
They do look like blue glass, at the back has something that makes this effect of cats eye, they shine with light, the reflection of light on them moves the sparkle.
This is the best I can describe them.
I am going to read a bit about foiled glass jewellery, it’s something I wanted to do for some time.
Will post the new photos tomorrow.
Kind regards,
Simona

 

a seller not to be trusted......

 

Could they be Morpho butterfly wing under glass? Can you get some close up photos?
If you are using an iPhone the Camera +2 App has an excellent Macro setting.

 

Morpho is a thought.

 

They are unusual, I have never seen polished cabochon of….. Paua shell, well spotted @evelyb30 ”glass-topped "glacier pearl", aka paua shell.” It was confusing because of the glass top, as I have never seen Paua shell so smooth.
Looked at it with a magnifying glass, it has shades of green and blue, and something that looks like moss.
How did I reached to this conclusion?
I cleaned the back of one of them, please have a look, it’s fascinating.
Any educational links on “glacier pearl”, please share.
Thank you all so much.
Xx @Bronwen
@KSW

 

Found this on Morpho butterfly wing, new information, thank you for sharing @KSW
https://bugunderglass.com/product-category/real-butterfly-wing-jewelry/page/2/

 

Definitely paua. Very pretty.

Paua shell is mother of pearl, it can be polished just as much as white MOP.

That's what they looked like to me too, which only goes to show how important photos of the backs are. (And full size photos.)

 

Is Paua Shell the same as Abalone? From the back that's what it looks like to me.

 

Paua is a specific black abalone from New Zealand. Paua is a New Zealand Maori name.
The paua themselves are black sea snails, and their MOP is the darkest and most colourful MOP of all.

 

These are so beautiful ❤️
I agree, paua shell.
Those would be in my ears ASAP!

I will add that pushing those earring backs over the threaded posts will eventually ruin the threads.
Assuming you will keep and wear them, I suggest replacing with plastic backs to avoid this. If you found threaded backs somewhere, chances are that they wouldn't fit the threads on the earrings.

 

Stunning is really what they are!

 

TY as soon as I saw that back closeup I was thinking abalone.

 

abalone does indeed come in dark colors as well..

 

Very pretty! And secure to wear. I have 14 k gold with transparent white glass studs the are pierced screw-threaded backs like these ones, and I am very happy with them. The only trouble is that if you sleep with them, the backs are quite long and can press the flesh behind the ear, and you have to move them away - not take out but just move at a different angle against the skin. And go to sleep again.