Bapi Bera and Rakesh Sonker it is not that simple. Carbides (e.g., SiC) and CO/CO2 are considered inorganic compounds, for example. Diamond is not considered organic either. Carbon nanotubes, fullerene, graphene and graphene oxide are allotropes of carbon, such as diamond, and therefore are not considered organic either. The criterion to determine if a compound is organic or inorganic is quite obscure to me, however, we should avoid simplist definitions.
Allotropic forms of carbon are based on the different degree of hybridisation of the carbon atoms.
sp3 (diamond), sp2 (graphene) and sp1 (carbynes) are the three allotropic forms of carbon.
Diamond is considered an organic material.
Fullerenes are organic molecules which have strained sp2 hybrid bonding, but should be considered in the same category as graphene, as should, for example coronenes.
C70 is an organic molecule, but can be considered the shortest nanotube.
When is a molecule to big to be considered a molecule?