Which allotrope of carbon is used in ornaments?

1. Carbon exhibits many allotropic forms - both crystalline and amorphous.
2. Diamond, graphite, and Fullerenes, graphene are the allotropic forms of carbon.
3. Diamond is used in the making of ornaments.
4. Diamond has a three-dimensional rigid structure of carbon atoms which are very difficult to break and are covalent in nature.
5. Since these bonds are difficult to break and hence it is the hardest substance on earth.
6. Therefore, diamond is used as a precious stone and is used in jewelry.