Hearts and arrows symmetry is the share of a hearts and arrows pattern where all sixteen halves match. Our Hearts & Arrows Scope gives it as a whole percent for each view.
In more detail
Proportions alone never lower it, because they change every half in the same way. Small faults do: in the T73 in diamond, mains up to 0.1° off give 90% face-up and 85% face-down. It differs from a report symmetry grade and from our light-performance symmetry score.
How we measure it
We lay a polar grid of 32 angles by 96 radii over one half-sector. We trace each point in all 16 of its images. A point counts when all 16 show the same color, weighted by its radius. 100% means every point agrees.
Related terms
- Hearts and arrows: Hearts and arrows is a pattern that a precisely cut round brilliant shows in a reflector viewer. Face-up it shows eight arrows, and face-down eight hearts.
- Hearts & Arrows Scope: The Hearts & Arrows Scope is a free Digital Gemology tool that simulates a hearts and arrows viewer. It shows a round brilliant's arrows face-up and hearts face-down, with one symmetry figure per view.
- Symmetry (light performance): In our light-performance scores, symmetry measures how evenly the pavilion facets of each angle family are cut. It reads 100 when every facet in a family has the same angle and distance from the center.
- Symmetry: Symmetry is the report grade, from Excellent to Poor, for the exactness of a stone's outline. It also covers the shape, placement and alignment of the facets.