What is symmetry in a diamond or gemstone?
By Jared James · Last updated 21 May 2026
Definition
Symmetry is one of the three components of a diamond's cut grade, alongside polish and proportions, and it describes how precisely and evenly the facets are shaped, aligned and balanced across the stone. Good symmetry means each facet is where it should be, every opposite pair lines up properly, and the girdle runs level. When symmetry is poor, facets may be off-centre, misshapen or uneven, which disrupts the way light travels through the stone and slightly dulls the overall brilliance. Grading labs like GIA score it from Excellent down to Poor.
Frequently asked questions
- How much does symmetry affect a diamond's appearance?
- For brilliant-cut diamonds, small symmetry imperfections are usually invisible to the naked eye, so a grade of Very Good is quite acceptable. Ideal-cut diamonds and fancy shapes like ovals are more sensitive to symmetry issues, where off-centre facets can create a visible bow-tie shadow or uneven sparkle.
- What symmetry grade should I look for in a diamond?
- For most round brilliant diamonds, Very Good or Excellent symmetry is the practical target. Going below Very Good can start to visibly affect the stone's light performance, especially in premium cuts. You can often trade a Very Good grade for a slightly larger stone without noticing any real-world difference.
- Is symmetry the same as cut grade?
- Symmetry contributes to the overall cut grade but is assessed separately. Cut grade also takes into account the stone's proportions, such as depth and table percentage, and its polish. A stone can have excellent proportions but still earn a lower cut grade if its symmetry or polish is weak.
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