I am a graduate student taking an appraisal course at FIT.  I am
trying to ascertain or verify really, some of my ideas about the
history of and the technique used to make this brooch.  It's clasp
tells me it is from the 1890's, as does its subject matter and provenance.  I think
the scence depicts Thisbe & Pyramus, though I am not positive.  The
brooch is oval with a thin twisted silver wire as its framing.  The
figures are white, background blue.  It seems to have many layers, IF
it is a limoges cameo. It is glazed, I think it's porcelain, but I
don't know how to tell that either.
The back is stamped "Made in France"  in a circle with the word
"Limoges" through the middle of that circle.  Can anyone tell me where to look for
definite answers to support this information.  Also, I need to figure
out how much it is worth, in order to write a Retail Replacement Value
Appraisal.  ANY help offered is most generous of you.  Thanks.

While I am no expert this is what I learned:

"Made in" indicates that the item is of 20th century manufacture. 

link to limoges society: 
http://www.limogessociety.com/pendants.html
link to encarta pottery: http://encarta.msn.com/encyclopedia_761568150/Pottery.html

Hope this helps

any pic? if limoges, certainly porcelaine, is it signed or something??
any little signs?