Help me ID 3 rings?

[antiqography]

Hello! I'm new to the forum and to vintage jewelry in general so any help you could provide me would be appreciate greatly! I bought a "lot" of rings and these 3 are really puzzling me.

The first is what I would assume looks like foil backed glass but I can't find anything similar online. It has arrows up the sides, it's marked "Sterling Si..." and "Made in En...". I know ZERO about foil backed gems and paste so I don't know if it's new and made to look old or if it's really old and something special. Help?
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The second star ring is marked 925 and I assume those are marcasites but I can't figure out the other gems. They look a bit more gray in person. Any ideas?
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The abalone ring has 3 markings "MO" or "MD", 925 and "THA". Any idea on maker? Maybe Thailand?
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Thank you to anyone who tries to help this novice.

 

[foxinsox]

Can you post any pictures? Preferably in focus, close up and in natural/diffuse light.

 

[antiqography]

Can you post any pictures? Preferably in focus, close up and in natural/diffuse light.

I embedded them in the post, I guess it didn't work?View media item 122317View media item 122318View media item 122316View media item 122315View media item 122314

 

[antiqography]

Please let me know if they didn't post above. I'm not sure what I'm doing wrong.

 

[Katesimone]

I can't see the pics either

 

[antiqography]

Well crap. I am determined now. How about this link?

http://imgur.com/a/wkqpf

 

[Tourmaline]

The blue glass one is the most interesting, but none of these are rare. The one with the marcasites has either semiprecious stones (like treated topaz), or synthetic. They're worth under $10 each.