Stunning metal cameo/portait on filigree pendant necklace

Stunning metal cameo/portait on filigree pendant necklace. This unusual pendant shows an incredibly detailed profile portrait of beautiful woman, mounted to a scroll work base. Comes with 28 in chain, pendant 1.75 in diameter. This necklace is not marked, but shined very well during cleaning. I know very little about this piece, except that it was part of my grandmother's collection. So I'd has to be 198Os or earlier. Such an amazing piece. Pictures don't do it justice.