Featured Opal Doublet? Silver Dangle Earrings

I’ve googled and looked at Opal Doublets online but I’m still unsure if this is what I’m looking at here?
I can still see fire when I look through from the side so is the top part Opal or is that reflection? Is it made to look dark by the silver setting or is it naturally dark? Or is there no way to tell once it’s in a setting? Setting is marked st/s but I don’t think the posts are as the bobbly bits are brass.
Is the setting likely modern in some countries despite not having the 925 mark? Or does St/S give them some age?
So many questions…….Any thoughts welcome please
Thankyou

 

A doublet can be an opal slice with a top cover (resin, glass, quartz) for protection/cost reduction, or a top cabochon with a backing (usually dark) to enhance the colour. From the side on images yours looks like the latter.

 

Very pretty, K. The style looks 1970s to me, but jewellery after 1940 is not my forte.
The cabs look like opal doublets on a dark base, as Ce said.

 

Ah that’s very helpful,Thankyou….
(Random scrabbling around in a box)…
So this one is a triplet as the Opal is under a glass top.

 

Thankyou

 

I believe opal chip slices in between a base and top layer would be called 'mosaic opal'.
A triplet has one single slice of opal over the entire surface of the base, and a protective layer on top.

These are triplets:

 

Ok, got it! Thanks

 

Mosaic opal are triplets,a base layer,opal layer and "glass" cap.