Scottish Skean Dhu

[Sajen]

Originally Posted by Battara

The stone may also be glass - very common in these.

I think that it is like Krockew write a cairngorm, some sort of smoky quartz found in the Cairngorm Mountains of Scotland, see here: https://en.wikipedia.org/wiki/Smoky_quartz

But of course it could be very well glass, to be sure I would show it to a jeweler.