Which term is the exactness of a finished gem's shape and facet placement?

• A. The total distance a light ray travels in a gemstone.
• B. The change in speed and possible change in direction as light travels from one material to another.
• C. The light reflected at a boundary between materials.
• D. The exactness of a finished gem's shape and facet placement.

Answer: (D)

Focus on how precisely a gem is shaped and facets are placed. The exactness of a finished gem’s shape and facet placement is described by its cut. Cut covers the overall geometry, proportions, symmetry, and facet alignment, which together determine how light is reflected and refracted inside the stone and, ultimately, its brilliance. The other options describe light behavior—optical path length, refraction at material boundaries, and boundary reflection—because they refer to how light travels or changes direction, not to how the gem is shaped and facetting arranged. So the term that fits this description is cut.