Help with stone in Egypian Revival bracelet?

[hertzgirlz]

I want to list this Egyptian revival bracelet but I can't figure out what is going on with the center stone.  It looks like it has something growing on it--it is smooth and black underneath with a crackle like coating on some of the top.  Has the coating just worn off the part where the black is exposed or is there some disease or something attacking the stone? I have tried to peel more of the coating off but it seems to be stuck fast. Any ideas are welcome!

[old.crows.nest]

Might be made to look like Ancient Glass but hard to tell on my tiny screen.

[cleio]

My guess is that it has some kind of corrosion on it 😞

[old.crows.nest]

I tried saving the image to a folder so I could view it better and am thinking maybe it was a a nugget or lava stone that has a chip missing. Maybe a Stone similar to the ones HAR used in their snake jewelry?

[hertzgirlz]

It does look like a chipped lava stone under the yuck.  I am leaning toward some kind of corrosion also, but I can't figure out why it won't chip or scratch off at least a little bit--do you suppose it is fused onto the stone?

[calis_stuff]

Does the gunk 'grow' onto the setting ? If it does, I'd think it was corrosion.

[calis_stuff]

I think I see where a prong is over the stuff with no sign of being affected, that might make me think it's deliberate.

[dream*peddler]

The only thing I can think of is that it looks like the outside of a geode.  Is the underside of the stone affected?

[hertzgirlz]

I popped the stone out and there is no sign of the gunk on the setting but it is covering most of the back of the stone except for one part near the top where there is another chip to the base stone--I think it was actually meant to be on the stone and when the black stone chipped it chipped off with it. The other two round stones on the bracelet have a rough surface so I think it maybe it is the same kind of finish but not as pronounced. Very weird!

[ifmelfalls]

Very weird indeed. I'm definitely interested if anymore information is found out regarding it. 

[old.crows.nest]

I am still thinking Faux Ancient Glass for all because of the Egyptian theme. If you look up "Ancient Roman Glass" you might see examples or crusty glass that looks like the surfaces of the stones in your piece.

[hertzgirlz]

I did look up ancient Roman glass because I was not familiar with it and saw a couple examples that resembled this finish, but was the underlying stone black glass or some form of obsidian?--that would make sense if the ancient Romans used the cooled volcanic magna i.e. obsidian.  I think perhaps this is not actual ancient glass but a finish applied to black glass to mimic it. I may just include all these thoughts in the description and let the buyer decide.

[hertzgirlz]

Here are a couple photos of the back of the stone:

[old.crows.nest]

For comparison there is a section in this Article on Ancient Glass:

http://sadighgallery.blog.com/page/4/

[hertzgirlz]

Very interesting article--thanks for the link!