Explain why is coal known as black diamond?

Explanation

**Step-by-Step Solution:**

1. **Understanding the Term "Black":**
- Coal is referred to as "black" primarily because of its color. When we observe coal, we notice that it has a deep black appearance. This characteristic is the first part of the term "black diamond."

2. **Understanding the Term "Diamond":**
- The term "diamond" is associated with something that is precious, valuable, and essential. Diamonds are known for their high value and significance in various industries, particularly in jewelry.

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