Your post told me more about turning mammoth tooth than carbide sharpening. But, that is a good thing. I believe I will pass on trying to turn that material. However, your results with that pen are stunning. Enjoy using or sell for top dollar. BTW, the hardest material I have ever turned was some faux ivory (not what the pen supply vendors sell). Results were beautiful but time and effort have dissuaded me from using the one blank I have left. Maybe one day. BTW, the carbide turning tools I use I made myself. The cutters are replacements for planers and jointers. They cost under $5.00 each and have four edges. I don't bother to try resharpening. For any material other than actual rock and glass, one edge lasts almost indefinitely.Not long ago I made a pen from Mammoth tooth. As I blunted the four facets i removed them from the tool and placed them cutter face down on a fine Diamond file. I had to do this ten to fifteen times,each time restoring a useful cutter group. I am still using that one so it works for me. The surface was bands,really hard,about 4 -5 hrs turning.rock and glass.
Good luck with your needs.