Butterfly brooch with agate? wings? Any help would be appreciated

[laboutiquegarage]

This piece is not magnetic but did not test sterling yet it is tarnished. I can't make out the stamp. It's 3 initials G, Eor F, K or R for the last one. I tried to get a photo but not working out very well. The wings are white with green here and there, I though agate. The tops of the wings are carved. It looks aged but I've been fooled before. Any help would be appreciated.

Thanks

Donna

[bijom]

Hi ,

The wings appear to be jadeite.

I had a similar piece and the metal setting turned out to have a plated surface with a copper/brass base.

[birdonawire27]

Looks like White Nephrite Jade in silver setting 1920's to 1940s.