A pure graphite pencil which has a diamond blade at the other end. This is made by taking a hexagonal column of graphite and applying extreme pressure and heat to half of it along a transverse axis, squashing it and converting it to diamond. This enables one end to be used as a very durable, sharp blade and the other as a writing implement. Alternatively, the blade can be used as a pen by drawing blood and writing with it. It needs to be held with some kind of spongy protective holder when written or drawn with.

I have a question. If the pressure in forming such a device is applied as a gradient, are there intermediate graphite/carbon allotropes and if so, what are they like?

Obviously you'd throw it away when you ran out of graphite.
-- nineteenthly, Jan 08 2017

https://www.newscie...s-hardest-material/ [hippo, Jan 09 2017]

If you break it in half you can sharpen the pencil.
-- whatrock, Jan 08 2017


Hardness and durability are different things.
-- Voice, Jan 08 2017


I don't think there is a smooth transition. The heat/pressure will make a fracture gap.

Maybe if the intervening Carbon continuum was all different C containing molecules, just like the Metamorphosis print, then you could get something that stuck to graphite and transition to something that stuck to/into diamond. All solidified with pressure and heat.

Also thanks I will look into the canadian programme Continuum.
-- wjt, Jan 09 2017


Is there a reason why there can't be bits of graphite embedded in diamond or vice versa? What happens with black diamonds?
-- nineteenthly, Jan 09 2017


Diamond would make a fairly crappy knife blade. It's way too brittle (as well as not being heat-resistant, etc.)
-- hippo, Jan 09 2017


Wurtzite boron nitride, of course (see link)
-- hippo, Jan 09 2017



random, halfbakery