Which lighting condition should be avoided when trying to observe a diamond's fire?

• A. Direct spotlight
• B. Natural daylight
• C. Fluorescent diffused light
• D. Incandescent light

Answer: (C)

Observing fire in a diamond relies on a light source that provides a broad, continuous spectrum with good color rendering so the dispersion of colors inside the stone can be seen clearly. Fluorescent diffused light tends to deliver a limited or uneven spectral output with color skewing, which can wash out or distort the rainbow colors that make fire visible. In contrast, direct lighting, natural daylight, and incandescent light all offer broad spectrum, high color accuracy, and enough intensity to reveal dispersion and sparkle. For the most vivid fire, avoid the fluorescent diffused option.