Which one of the following allotropes of carbon is used for cutting and drilling ?

Diamond is the allotrope of carbon used for cutting and drilling due to its exceptional physical properties. It is recognized as the hardest natural substance known [c1][c2]. This extreme hardness arises from its three-dimensional structure where carbon atoms are joined in a rigid, strong shape with a Mohs hardness of 10 [t5]. Because no other naturally occurring substance can scratch or cut it, diamond is the dominant material for industrial applications involving cutting, drilling (drill bits), grinding, and polishing [t1][t3]. While other allotropes like graphite are soft and slippery, making them suitable as lubricants, diamond's rigid lattice and thermal conductivity make it ideal for embedding in drill tips and saw blades [t4][t5]. Approximately 80% of mined diamonds, known as bort, along with synthetic diamonds, are dedicated to these industrial manufacturing purposes [t1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > Allotropes of carbon > p. 61
2. [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Table 3.1 > p. 40
3. [3] http://afrodita.rcub.bg.ac.rs/~rzoran/Allotropes%20of%20carbon.htm