Massive opal river pattern koroit raw polished untreated gemstone unisex pendant

A pendant, large pendant too, of koroit opal from Australia with a solid sterling silver surround.
 
The piece is opal that runs as rivers through a host rock, this is a piece that is organic and is only polished and mounted so as to wear.
 
The piece has mostly greens but blues and reds, oranges and even purple sparkles!
 
I do have more, I have this piece, however this is for ornamental use as it is too large to wear as a pendant: https://www.treasurentreats.com/product-page/195ct-untreated-koroit-boulder-opal-natural-sedimentary-layered-multicolour-gem 
 
The buyer can have this stone tested by GIA, 1 year extended warranty. Any treatments found return stone for full refund.

Please note that photos will appear different, monitor to monitor however I do not use any photo modification, photo adjustment or special lighting. 
 
The worlds largest Mexican fire opal piece available from my Etsy shop: https://www.etsy.com/uk/listing/1045023024/9422ct-untreated-yellow-opal-chinese?click_key=3f7a6efe5bf17e655f119fb51667f0015b27f1fc%3A1045023024&click_sum=d2ace2eb&ref=shop_home_active_3