Why Are Diamonds Hard?

Thanks to Dnews for providing some of the imfo in this vid, here's the vid:https://youtu.be/FBzv8pQYcdA


Sources:http://chemistry.about.com/od/geochemistry/f/Is-Diamond-A-Conductor.htm

http://chemistry.stackexchange.com/questions/12404/why-does-diamond-conduct-heat-better-than-graphite

http://chemistry.stackexchange.com/questions/12404/why-does-diamond-conduct-heat-better-than-graphite