The hybridizations of carbon in graphite, diamond and ${\mathrm{C}}_{60}$ are respectively

Diamond, graphite and ${\mathrm{C}}_{60}$ are known as allotropes of carbon. In diamond, each carbon atom is tetrahedrally bonded to four carbon atoms, forming a $3-\mathrm{D}$ network of strong,  covalently bonded carbon atoms. All carbon atoms are ${\mathrm{sp}}^3$ hybridized.

While in graphite and ${\mathrm{C}}_{60}$, each carbon is bonded to three carbon atoms, forming a network of hexagonal rings arranged in a plane in graphite and as sphere in ${\mathrm{C}}_{60}$. All carbon atoms are ${\mathrm{sp}}^2$ hybridized and have one free electron. Numerous such layers are bonded to each other via weak Van der Waals forces in graphite.