Featured Jewelies,silver or ....?

Hi all. Picked this up at an estate sale but am unable to find a mark. It looks stamped,and I thought it silver. I splashed out $7.50 on it,and you all know that pains me ! Its a pretty thing nonetheless. 2 inches long,1 1/2 wide.Pure Art Nouveau . Any input on it is always appreciated.

 

For example ...
https://www.etsy.com/listing/256681...=mucha+brooch&ref=sr_gallery-1-16&pro=1&frs=1

https://www.etsy.com/listing/252195..._search_query=mucha+brooch&ref=sr_gallery-1-1

http://www.muchafoundation.org/en/gallery/browse-works/object/92

 

I google searched my head off too,yet I found zilch. ! Thank you so much,now I know.

 

The back is telling me more modern than period Art Nouveau. In the 1980s there was a resurgence of interest and a lot of Art Nouveau style jewelry was made, I think it may be from then.