Amber rough material
Amber is basically petrified ancient tree sap. Because of that, it is a pretty soft material.
The age of the Amber and the degree of petrification can vary and because of that the hardness of Amber can vary a bit. It is never really 'hard' but some of it can be softer than others.
If your Amber gets scratches in it, it is soft that you can re-polish it yourself by rubbing it on your jeans for several minutes.