I’m not sure all the valve suppliers do it the same way, but custom Manley Ti valves can be ordered with or without hardened tips.
The hardened tip is easily seen if you’re looking for it(as well as being magnetic), and makes the tip length .049 longer.
Most Manley’s with hardened tips have a .290 tip length.
Ti valves w/o hardened tips require the use of lash caps.

The first pic is of a Del West Ti valve with a hardened tip.
If you look close you can see a slight different in color/texture at the top.
The tip length on that valve is about .310.

The second pic is what the top looks like after a few thousand miles of use in an 18* SBC that runs over 8000rpm lap after lap.