i have a black wedgwood cameo pendant, can you estimate the value?

by Bethany
(Beds, UK)

I have a black vintage wedgwood cameo it has a black backround and a white womans face on it (i think its a muse design), it has wedgwood stamped on back and has a code stamped on the sterling rim, it says jw but i cant read the rest of the letters. I have only seen two images of it online and i wanted to find out its value and if its rare, can you estimate the value?

The photo below is the design and colour