Another tool I have dug out of my collection that I'm not sure of its application. It appears to have a diamond in the point, which can be pushed back against the spring tension. Pulling the collar down only appears to increase the spring tension. The rod the point is attached too is a very nice fit inside, what looks like, a polished bore.

Any ideas?

Cheers, Craig

Interesting ideas everybody, thanks. The hardness tester idea is a good one but this item was in a pouch just big enough for itself and I would expect instructions as well as ancillary items.

Clive I have to be honest, that's a new one on me, and even after a quick Google it looks way over my head. But for that reason it could well be a possibility for all I know.

The engraver idea seems the most plausible, the drag engraving tools certainly share some resemblance it's just, as said, this item seems quite a bit bigger. It could have been used on a large machine though I suppose.

Thank, Craig