How is the new Cut grade on diamond certs different to a diamonds symmetry grade?
The symmetry of a diamond refers to how its facets are arranged in relation to each other to form a regular symmetrical pattern. A perfectly regular arrangement of facets aids the uniform transmission and reflection of light traveling thorough the gem needed to maximise the diamonds brilliancy. When judging symmetry diamond graders looks for how unvarying is the diamonds outline (e.g. is the outline of a round diamond a perfect circle), whether the table and culet facets are exactly centred in the diamond and whether the plane of the girdle is exactly parallel to the plane of the table facet when the stone is observed from the side. The grader assesses any discrepancies in the symmetry and assigns a symmetry grade as excellent, very good, good, fair or poor. One criticism of a diamonds symmetry grade is that it does not highlight poorly fashioned stones such as lumpy round brilliants and fish-eye stones. These are picked up by the new cut grade recently introduced by the GIA grading sy
