I have a necklace set with two blue stones that I always believed
was chalcedony. The blue was like the sky, and intense.
It has been in a bank vault for years and years, and the last time I
looked, one of the stones was turning white in areas and the other
seemed to have gotten a bit pale. The piece is German from the early
part of the 20th century, I think.
I may be wrong about the identification. I now wonder if it is some
other stone like a white onyx that was dyed blue. If so, what would
have made the dye wear off, sitting quietly in a bank vault?
If not, is there a blue stone that can fade in the dark, and looks
like blue chalcedony?