Carbon is capable of forming many allotropes due to its valency. Well-known forms of carbon include diamond and graphite, in recent decades many more allotropes and forms of carbon have been discovered and researched including ball shapes such as buckminsterfullerene and sheets such as graphene. Larger scale structures of carbon nanotubes, nanobuds and nanoribbons. Other unusual forms of carbon exist at high temperatures or extreme pressures. Around 350 hypotetical 3-periodic allotropes of carbon are known at the present time according to SACADA database, Diamond is a well known allotrope of carbon. The hardness and high dispersion of light of diamond make it useful for industrial applications and jewelry. Diamond is the hardest known natural mineral and this makes it an excellent abrasive and makes it hold polish and luster extremely well. No known naturally occurring substance can cut a diamond, except another diamond, the market for industrial-grade diamonds operates much differently from its gem-grade counterpart. Industrial diamonds are valued mostly for their hardness and heat conductivity, making many of the characteristics of diamond, including clarity and color. This helps explain why 80% of mined diamonds are unsuitable for use as gemstones, the dominant industrial use of diamond is in cutting, drilling, grinding, and polishing. Most uses of diamonds in these technologies do not require large diamonds, in fact, diamonds are embedded in drill tips or saw blades, or ground into a powder for use in grinding and polishing applications. Specialized applications include use in laboratories as containment for high pressure experiments, high-performance bearings, with the continuing advances being made in the production of synthetic diamond, future applications are beginning to become feasible. Garnering much excitement is the use of diamond as a semiconductor suitable to build microchips from. Each carbon atom in a diamond is covalently bonded to four other carbons in a tetrahedron and these tetrahedrons together form a 3-dimensional network of six-membered carbon rings, in the chair conformation, allowing for zero bond angle strain. This stable network of covalent bonds and hexagonal rings, is the reason that diamond is so strong.1 kJ/mol compared to graphite, graphite, named by Abraham Gottlob Werner in 1789, from the Greek γράφειν is one of the most common allotropes of carbon. Unlike diamond, graphite is an electrical conductor, thus, it can be used in, for instance, electrical arc lamp electrodes. Likewise, under conditions, graphite is the most stable form of carbon. Therefore, it is used in thermochemistry as the state for defining the heat of formation of carbon compounds
Computer models of stable nanobud structures
A large sample of glassy carbon.
The K4 crystal
Diamond and graphite are two allotropes of carbon: pure forms of the same element that differ in structure.