dark grey cab set stone. The stone seems to have an indistinct
layer of translucent at the top, like a moonstone
This is hard without a picture, but sounds like grey cat's-eye,
which actually is fibreoptics colored grey. Hope this helps some.
Karen Seidel-Bahr the 'ROCKLADY' @Rocklady K.I.S.
Creations May your gems always "Sparkle"