Diamonds are the hardest substance on earth fact or opinion

It is an fact. They are really hard to break.

As far as we know, this is true. Though they are very hard, like most network solids, they are also brittle if hit the correct way.

Structure your essay into an introduction, body, and conclusion. make sure your essay focuses on a main idea, includes precise language to clarify ideas, and is written in a formal style. use textual evidence, including scansion, to support your ideas.