Ancient semi-precious stone 835

I bought it as aqua-chalcedony (or water chalcedony), but I am not a mineral expert, so I cannot guarantee that this exact stone is in the pendant. It is a hazy blue-green, somewhat reminiscent of the depths of the South Sea :)
The stone is in an antique - 800 silver frame.
The chain is also vintage - 835 silver.
Total length - about 29 cm (*2).
Total weight - about 5.5 grams.
An old piece of jewelry in good condition, with possible surface wear appropriate to its age.
Shipping is not included and should be added according to the Andele price list.