Which term describes visible shadow-like lines in a diamond caused by glide planes?

• A. Graining (Grain Lines)
• B. Growth Marks
• C. Habit
• D. Resorption

Answer: (A)

Graining, or grain lines, describes the visible shadow-like lines found inside a diamond that follow the crystal’s internal lattice. These lines arise when there are slight misalignments or distortions along glide planes in the diamond’s crystal structure. When light travels through the stone, these areas of differing orientation scatter light a bit differently, creating the shadowy lines you can see with magnification or in certain viewing conditions. This is distinct from growth marks, which come from the crystal’s formation process; habit refers to the overall crystal shape, and resorption relates to dissolution of crystal material.