Jet ? Vintage Brooch

This is a really nicely carved black brooch which I brought back from UK a while ago now as jet.  On examination I am not absolutely sure that it actually is jet, and perhaps even the central piece carved with lily of the valley shaped flower and leaves is jet with a resin frame.  Nevertheless it is a very attractive black brooch measuring 4cms across with a traditional C clasp pin glued in to the back.   It is not priced as jet to be on the safe side.  It is in very good condition, gift boxed by Vintageonline.