What is the main cause of black, gray, and white colors in diamonds?

• A. Boron impurities
• B. Surface damage
• C. Inclusions
• D. Nitrogen impurities

Answer: (C)

The primary cause is internal inclusions and other internal features that scatter and absorb light. When a diamond has mineral crystals, fractures, or other imperfections inside, these inclusions disrupt how light travels through the stone. If many are present, they absorb more light and scatter it, creating dark spots (black), cloudy areas (gray), or a milky white appearance as the stone becomes less transparent. This is different from colors produced by impurities, such as nitrogen causing yellow/brown or boron causing blue. Surface damage affects the exterior luster rather than producing the internal dark or cloudy coloration.