Is this stone agate?

I bought this ring at an estate sale, so I have no background on it. The setting is 14K gold. Is the stone an agate? I'm clueless. TIA.

 

Can you do full on, back and sideways shots please?

 

I will. I'll take me a while to get it done. I'll repost when I've taken the photos.

 

Looks like operculum to me.

 

Is this stone agate? - No, it is astone..

 

A search of operculum jewelry:
https://www.google.com/search?sca_e...Z2oDWcQ0pQJegQIChAB&biw=1488&bih=1030&dpr=1.8

 

Is the top flat or convex? From the 1 blurry photo, it looks a bit like banded agate that has been prepared to be what is called nicolo. A thin white layer over a black one gives the effect of a blue surface. When engraved the design appears as black on blue.

 

That was my impression too.

 

Looking at it again I see the black at the back so agate seems more likely. Hopefully we will see better photos

 

Here are some better photos of the ring.

 

Assuming it is not glass, & there really is no reason it should be, appears to be more or less what we were describing: a 2 layer stone with a (dyed) black bottom layer & an uneven, very thin upper whitish layer giving that blue nicolo effect. The upper layer is not of even thickness all over; it fades out in the middle. So the answer to your question is yes, it is agate.

 

Thank you.