This Is a Certified Answer

Certified answers contain reliable, trustworthy information vouched for by a hand-picked team of experts. Brainly has millions of high quality answers, all of them carefully moderated by our most trusted community members, but certified answers are the finest of the finest.
Both the carbon allotropes have a different arrangement of carbon atoms in them, here, in diamond carbon-carbon covalent bond is formed by with all carbon atoms bonded.
while in, Graphite they are arranged in rings and overlapping layers bonded by weak van der Waal forces resulting free electrons.
As you know flow of charges is current, graphite is left with free electron which can flow but not with the case of diamond.