This is a lot of 4 assorted hardness indenter tips, used for testing hardness of materials.  There's not much on these for identification, though two appear to be diamond-tipped and two others possible metal tipped.

All sold as pictured, I have no idea on the


Listing Includes: 

• STC N-Scale Hardness Indenter - 200139
• STC C-Scale Hardness Indenter - 180945
• 113502 Hardness Indenter
• 113506 Hardness Indenter