The form of carbon which is used for cutting and drilling rocky glass is __________

Explanation

**Step-by-Step Solution:**

1. **Identify the Forms of Carbon**: Carbon exists in several forms, the most notable being diamond and graphite.

2. **Understand the Properties of Diamond**: Diamond is known for being the hardest natural substance. Its structure is a three-dimensional crystalline arrangement, which contributes to its hardness.

3. **Determine the Use of Diamond**: Due to its hardness, diamond is commonly used in applications that require cutting, drilling, and grinding. This includes cutting through tough materials like rock and glass.

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