I've been trying to track down the meaning behind this symbol.
I received this as a gift from my mother, the only info I have is that my great grandfather sent this from Poland, would guess that it dates back to late 1800s to early 1900s. His family name was Ostrowski.
Any clues would be appreciated as this symbol is a mystery to us.
Are you sure it never had a stone in it? That lip and the markings make it look like a typical bezel setting, and the scratches are just what was on the bit of metal they bonded the wire to, or after they burred it a little to get the right shape.
There was nothing inscribed on the inside.
You might get answers here, but I'd consider crossposting to /r/whatisthisthing
The symbol is simply a monogram with the letters laid on top of each other and some detailing. It's difficult to read precisely without being able to examine it in person - you can usually twist it something that's been engraved in the light in order to catch all parts of the engraving - but I would say there's definitely an I, either a C or D (depending on which way is up), and possibly an E.
It's difficult to date, as it's both very simple and very worn. 1880-1920 is about as narrow a range as I could give you - the florid and ornamented style of the monogram is most typical of the 1880s-1890s, but it's totally possible for a retailer to have held onto some more "traditional" options in the first few decades of the 20th century.