Magnifying tool.

Sometimes called a jeweller's loupe.

This is a great one. It magnifies 6 times and 12 times.  

It is very old. The leather case has disintegrated at the flap end and the fastening button is missing.
I use it to get spelks out and to look at silver hallmarks.
It belonged to my late Auntie Eleanor. She died when I was a child. It was given to my Mam and then it went to me. 
Spelks are slivers usually of wood or thorns embedded in the skin. Apparently spelk is a North east word.