What is the most common cause of yellow color in diamonds?

• A. Nitrogen-related defects
• B. Boron impurities
• C. Radiation damage
• D. Inclusions

Answer: (A)

Color in diamonds comes from impurities or defects that alter how light is absorbed. Yellow is most commonly caused by nitrogen impurities in the crystal lattice. Nitrogen atoms substitute for carbon and form color centers; when nitrogen is isolated, the yellow can be vivid, while aggregated nitrogen tends to produce paler yellow or brownish hues. This nitrogen-related absorption specifically cuts blue light, so the transmitted light appears yellow. Other factors like boron impurities produce blue diamonds, radiation damage can yield green, and inclusions may tint a stone but don’t account for the typical yellow color as the primary cause.