Featured Any idea what this big round ball on ring is?

NOT MY HAND, LOL.
Seller simply describes this as "Deco Sterling Ring" and has no idea what the round ball is. Neither do I.
Any guesses? (Sorry, this is the only photo.)
Thank you!

 

Glass? Nice colour.

 

Nothing special, then? I liked the color, too.

 

Let's wait for the others. The ring itself looks a bit 'run of the mill', the ball makes it interesting.

 

Let it catch the sunlight, rotate the ball slowly, then let it rest. In a minute of so, a mist will cover the outside. Then, one must look deeply, through the swirling fog, into the center, and see...

 

Priceless.

 

It might be lucite. To me, the rings looks fairly new. Certainly not Art Deco.

 

The stone looks like that plastic that is sometimes called "Moon glow".

What is kind of odd is that this is on a sterling setting. Would expect it to be a base metal setting with the plastic, and would not have thought Art Deco either.

That said, here is one also sterling, two round stones, similar plastic and construction, calling it "Art Deco". I would not have said Deco, except the sterling gives me pause. I've been having trouble linking things, if it doesn't work will list item number.

https://www.ebay.com/itm/UNIQUE-ART...h=item441b78f9e3:g:NSkAAOSwEkhZ3MgV:rk:5:pf:0

 

The ring in the photo is a moonglow lucite bypass ring. The OP's might just be a "Pool of Light" ring in blue instead of the usual clear. Odds are good it's the lucite however, since glass would be awfully fragile for a setting like that. I've seen all sorts of costume bits in sterling settings made in the 40s, 50s and early 60s. I have two pair of those fake pearl button earrings with sterling screwbacks.

 

Think we can rule out sapphire, although the color would be consistent. The only other mineral I know that's a similar blue is kyanite, which is rarely used in jewellery & think would be too prone to fracture. In the photo it has a bit of moonglow quality; could just be lighting effect.