What primarily causes color in a diamond?

• A. Diamond color is primarily caused by defects in the crystal lattice.
• B. Diamond color is caused by surface polishing.
• C. Diamond color is determined by carat weight.
• D. Diamond color is caused by external coatings.

Answer: (A)

Color in a diamond mainly comes from how the crystal lattice interacts with light, controlled by impurities and lattice defects that create color centers. When trace elements like nitrogen or boron are present, they alter which wavelengths are absorbed, giving yellow, brown, blue, or other hues. Structural imperfections or defects in the lattice can also produce colors, such as pink or green tones, especially in fancy colored diamonds. Surface polishing affects only the surface finish and can influence brightness, but it doesn’t change the intrinsic color of the crystal itself. Carat weight is about size, not color, and external coatings would be a surface treatment rather than the natural color of the stone.