Diamond symmetry refers to the precise arrangement and evenness of a diamond's facets. A diamond's facets are the numerous flat surfaces that are cut into the stone to help it reflect light. Proper symmetry maximises the light performance, brilliance, and fire of a diamond.
What Is Diamond Symmetry?
Symmetry describes the alignment and placement of facets and other elements of a diamond's anatomy. If facets are misaligned or out of place, the diamond might not reflect light as efficiently or exhibit its maximum brilliance.
Key Symmetry Features
Symmetry involves evaluating:
- Alignment of Facets: Facets should meet without any noticeable gaps or overlaps.
- Centering of the Culet: The culet (pointed base) should be in the centre when viewed from the top.
- Table Symmetry: The table (top facet) should be parallel to the girdle (outermost edge) and centreed.
- Facet Shape and Size: Adjacent facets should be consistent in shape and size.
- Girdle Thickness: The girdle should exhibit consistent thickness, without wavy or uneven portions.
- Meet-point Symmetry: The points where facets meet should align correctly.
Factors Affecting Symmetry
Several factors can influence the symmetry of a diamond:
- Cutting Precision: The skills of the diamond cutter and the quality of tools and technology used.
- Original Rough Diamond: The nature and quality of the rough diamond can dictate certain cut decisions.
- Economic Factors: Cutting for weight rather than optimal symmetry can yield a larger, but less symmetric stone.
Grading Diamond Symmetry
The Gemological Institute of America (GIA) includes symmetry as a component of its overall cut grade. For round brilliant diamonds, symmetry is graded as:
- Excellent
- Very Good
- Good
- Fair
- Poor
Other grading entities, such as the American Gem Society (AGS), might use slightly different terminology, but the concept is similar.
Impact of Poor Symmetry
- Light Performance: Imperfect symmetry can misdirect light, diminishing brilliance and fire.
- Visual Distortions: Poor symmetry can produce noticeable visual effects, such as a "bowtie" appearance in elongated shapes like ovals or marquises.
Symmetry vs. Polish
While both are components of a diamond's finish, symmetry and polish are distinct:
- Symmetry deals with facet arrangement and alignment.
- Polish refers to the quality of the facet surfaces themselves.
Expert Tips
- Trade-offs: A diamond with minor symmetry flaws might still exhibit strong brilliance if other cut parameters are excellent. However, diamonds with significant symmetry issues should generally be avoided.
- Magnification: Always inspect diamonds under magnification (at least 10x) to assess symmetry accurately.
- Certifications: Purchase diamonds with certifications from reputable grading laboratories to ensure accurate symmetry assessments.
While symmetry is just one of many factors contributing to a diamond's overall beauty and value, it plays a critical role in a gem's light performance. A symmetrically well-proportioned diamond will display a harmonious balance, resulting in the captivating sparkle that diamonds are renowned for. Whether you're a jeweller or a consumer, understanding the intricacies of diamond symmetry ensures an informed and satisfactory selection.
