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

• A. Optical Density
• B. Refraction
• C. Symmetry
• D. Total Internal Reflection

Answer: (C)

Symmetry is the term that defines how precisely the finished gem’s shape and facet placement are aligned. In a well-cut diamond, the facets should meet cleanly and align along consistent axes—table centered, culet properly positioned, and girdle facets evenly spaced around the circumference. When symmetry is high, facet junctions line up as intended and the overall geometry is balanced, which helps light reflect and refract exactly as designed to maximize brilliance and sparkle. The other terms describe light’s behavior rather than the gem’s physical geometry: refraction is the bending of light as it passes between materials, total internal reflection is the light-trapping effect inside the diamond, and optical density isn’t a standard term used for assessing a diamond’s shape or facet placement.