Vintage/antique sterling silver (tested) green gemstone (chrysoprase?) & Art Nouveau or Arts and Crafts brooch /pendant with sterling chain

Beautiful Art Nouveau or perhaps Arts and Crafts antique sterling silver and green gemstone brooch that is also a pendant. So, included in the sale is a 17 inch slim sterling silver chain.

The pendant is beautifully made with pretty foliate leaf decoration around the sterling silver frame which holds a large, oval, green gemstone flat cabochon. I believe this stone is chrysoprase rather than another type of green agate or jade. I am not a gemologist though, so these are just my thoughts on the stone.

The brooch/pendant is not stamped by tests positive for sterling silver. The spring ring clasp of the chain necklace has a tiny 925 stamp for sterling silver. I have added the chain to the piece, so it may be slightly less old than the brooch/pendant.

It is in very good vintage condition - the smooth face of the cabochon is not at all scratched, it has been kept carefully. I try not to over-polish vintage and antique jewellery to maintain its original condition for as long as possible, but this piece would clean and polish more for wearing if desired.

If it is indeed chrysoprase, apparently:
Chrysoprase is a rare, highly valued, and apple-green to deep green variety of cryptocrystalline chalcedony (silica) coloured by nickel. Ranging 6.5–7 on the Mohs hardness scale, this durable gemstone is popular for jewellery. Often called "Australian Jade," it is prized for its translucent, vibrant colour and is commonly found in Australia, Brazil, and Germany.