Squares or rectangles, trigons and parallel grooves are types of what features observed in rough diamonds?

Squares or rectangles, trigons and parallel grooves are types of what features observed in rough diamonds?

• A. Cleavage lines
• B. Growth marks
• C. Habit features
• D. Luster patterns

Answer: (B)

Growth marks are surface features on rough diamonds that record how the crystal grew in the mantle. As a diamond forms, changes in growth conditions create tiny steps and interruptions in the crystal lattice, which show up on the surface as lines, geometric patterns, and grooves. Squares or rectangles, trigons, and parallel grooves fit this idea because they reflect the cube-like crystallography and staged growth of the diamond. Cleavage lines would appear as straight planes of weakness where the stone could be split, not as geometric surface markings. Habit refers to the overall crystal shape, not these small surface markings, and luster patterns describe light reflection rather than growth history. So, these shapes are characteristic of growth marks.

Growth marks are surface features on rough diamonds that record how the crystal grew in the mantle. As a diamond forms, changes in growth conditions create tiny steps and interruptions in the crystal lattice, which show up on the surface as lines, geometric patterns, and grooves. Squares or rectangles, trigons, and parallel grooves fit this idea because they reflect the cube-like crystallography and staged growth of the diamond. Cleavage lines would appear as straight planes of weakness where the stone could be split, not as geometric surface markings. Habit refers to the overall crystal shape, not these small surface markings, and luster patterns describe light reflection rather than growth history. So, these shapes are characteristic of growth marks.