The brilliance of diamond is due to

Options

A. Reflection of light
B. Refraction of light
C. Total internal reflection of light
D. Diffraction of light

Answer

To solve the question "The brilliance of diamond is due to," we need to understand the concept of total internal reflection and how it applies to diamonds.

### Step-by-Step Solution:

1. **Understanding Brilliance**: The brilliance of a diamond refers to the way it reflects and refracts light, creating a sparkling effect. This is a key characteristic that makes diamonds highly valued.

2. **Total Internal Reflection (TIR)**: Total internal reflection occurs when light travels from a denser medium (like diamond) to a rarer medium (like air) and strikes the boundary at an angle greater than the critical angle. At this point, instead of refracting out of the diamond, the light reflects back into the diamond.

3. **Critical Angle**: The critical angle is the angle of incidence above which total internal reflection occurs. For diamond, this angle is relatively small due to its high refractive index.

4. **Well-Cut Diamonds**: The brilliance of a diamond is enhanced by how well it is cut. A well-cut diamond is designed to maximize the amount of light that undergoes total internal reflection. The facets of the diamond are angled to ensure that light entering the diamond reflects off the internal surfaces multiple times before exiting.

5. **Conclusion**: Therefore, the brilliance of a diamond is primarily due to the phenomenon of total internal reflection of light, which is maximized by the diamond's cut.

### Final Answer:
The brilliance of diamond is due to total internal reflection of light.