Featured Glass or stone?

I found this cute little brooch today at the charity shop. It tests as silver but I'm trying to figure out the stone. I thought I saw air bubbles so I'm pretty sure it's glass, but it went up by one bar on the gem tester. I thought glass would not react?

​

 

Lovely, Rachel. It looks like a Scottish Cairngorm brooch.

Glass is 5-6 on the Mohs scale, so a hardness tester will react to it.
A Cairngorm can be citrine or smokey quartz, but sometimes glass was used.

 

I concur...

 

That’s a very nice mid to late nineteenth silver brooch. In the Scottish style as made fashionable by Queen Victoria. I agree it might well be Cairngorm.

 

Oh!! I did think it was scottish, but it sounds a bit more special than that yippee!

I thought this would date to 1900-1910 because of the length of the pin, also there's barely any room between the pin and the brooch for any sort of thick material, but I guess if its not worn on 'normal' attire it would be different?

I'll try to get a photo of the air bubbles I thought I saw. Hopefully they're not!