The chemical composition of diamond and graphite are carbon

scientists call "homogeneous much like variant", there are also known as "allotropes." From this call may know that they have the same "quality", but the "shape" or "sex" is different, and there diamond cup grinding wheel  is a world of difference, diamond is the hardest substance, while graphite is one of the softest material. We all know that with graphite pencil and clay ratio and made of graphite as many soft, with a "B" indicates, more than the hard clay mixed with "H" represents. Mineralogist with Mohs hardness expressed relative hardness, diamond is 10, while graphite is only a Mohs hardness. Their hardness big difference lies in their internal structure is very different.
 Graphite carbon atoms are within the layered arrangement, only around one carbon atom with three carbon atoms attached, form a carbon to carbon hexagonal ring, an infinite number of a layer of hexagons. Contact force between the layers is weak, and contact layer is firmly three  ceramic tile saw carbon atoms, by the force between layers so it is easy to slip, which  is very soft to write graphite causes.
 Diamond carbon atoms are within the "skeleton" shaped arrangement of three-dimensional space, one carbon atom is surrounded by four carbon atom, thus forming a three-dimensional space in a skeleton-like, this structure is uniform in all directions, contact force, very strong coupling, Therefore, the diamond has a high hardness properties.
 Graphite and diamond hardness vary so much, but people still want to be able to get the diamond synthetic method, because the nature of graphite (carbon) reserves are very rich. But to make the  bandsaw blades carbon graphite are arranged into a diamond like carbon, is not so easy. The late eighteenth century, people began to look for ways of synthesis, until the mid-century. 1938 Rossini scholar thermodynamic calculation, laid the theoretical foundation of synthetic diamond, calculated to make the graphite into a diamond, at least at 15,000 atmospheres, 1500 degrees Celsius under high temperature conditions can, to built 50-60 years to achieve the above conditions Instrument. Graphite 5-6 million atmospheres ((5-6) × 103MPa) and 1000 to 2000 ° C temperatures, then the metallic iron, cobalt, nickel and the like as catalyst, can graphite into diamond.