Symmetry
How precisely a diamond's facets are shaped, aligned, and positioned relative to each other — graded Excellent to Poor by GIA.
KEY FACT
Symmetry and polish are the two "make" grades. For a triple-Excellent round (Excellent cut / Excellent symmetry / Excellent polish), both must be Excellent. Very Good symmetry has negligible effect on appearance but comes at a useful discount.
5 grades
EX · VG · G · F · P
10×
GRADED AT
≥ VG
RECOMMENDED FLOOR
SYMMETRY GRADE
FACE-UP FACET PATTERN · DEVIATIONS EXAGGERATED FOR ILLUSTRATION
Symmetry deviations are invisible to the naked eye at Excellent–Very Good and subtle at Good. The illustration exaggerates differences to show the concept.
Excellent
EXFacets are precisely shaped and aligned. No deviations visible at 10× magnification that meaningfully affect appearance. The standard for Hearts & Arrows stones and triple-Excellent rounds.
Very Good
VGMinor deviations that are difficult to see under 10× magnification. Excellent light performance; nearly indistinguishable from Excellent in normal viewing. Very common in fine commercial goods.
Good
GNoticeable deviations under 10× that are not visible face-up to the naked eye. Still attractive and bright. Appropriate for buyers prioritising value over technical perfection.
Fair
FDeviations visible face-up under 10× and possibly to the naked eye in bright light. Noticeably affects the visual pattern and light return. Not recommended for engagement ring centres.
Poor
PSevere deviations visible to the naked eye. Light return is noticeably compromised. Pattern is irregular. Typically the result of cutting shortcuts or heavy repolishing.
What GIA evaluates
GIA checks eight specific types of symmetry deviation at 10× magnification. Each one can independently deduct from the grade.
Alignment
Off-centre table
The table facet is not centred over the culet. Creates an unbalanced face-up appearance — one side of the crown looks wider than the other.
Alignment
Off-centre culet
The culet (or pavilion apex) is shifted from the centre of the stone. Disrupts the symmetry of the pavilion facet pattern.
Girdle
Wavy girdle
The girdle undulates up and down around the stone rather than lying in a flat plane. Causes irregular facet sizes and misaligned main facets.
Girdle
Out-of-round girdle
For round brilliants, the girdle outline is not a true circle — it is slightly oval or irregular. The stone does not measure the same diameter in all directions.
DiamondTheGuide alignment
Misaligned facets
Crown and pavilion main facets do not meet precisely at the girdle — they are offset in rotation. This is a key cause of a broken or absent Hearts & Arrows pattern.
DiamondTheGuide shape
Unequal facet size or shape
Facets that should be identical — the eight crown mains, for example — differ in size or shape. Creates an uneven pattern under reflected light.
Surface
Naturals / extra facets
Small unpolished patches of the original rough surface (naturals) left on the girdle, or extra facets added to polish out inclusions. Both are symmetry deductions.
Alignment
Table not parallel to girdle
The table plane is tilted relative to the girdle plane — the table appears to slope when viewed from the side. Disrupts crown uniformity and the visual balance of the stone.
SEVERITY
Symmetry, polish, and cut grade
Three separate grades on a GIA report — and they interact in a specific way.
OVERALL CUT GRADE
Cut
GIA's cut grade for round brilliants is a holistic assessment of proportions, symmetry, and polish combined. It is the primary grade buyers should prioritise. A stone can have Excellent proportions but still receive Very Good cut if symmetry is poor.
Only issued for standard round brilliants
MAKE GRADE 1
Symmetry
Evaluates the precision of facet alignment, shape, and placement. Together with polish, these are the "make" grades — they describe execution quality independent of the chosen proportions. A high symmetry grade is especially important for Hearts & Arrows patterns.
Issued for all shapes
MAKE GRADE 2
Polish
Evaluates the smoothness of the polished facet surfaces — whether they show polish lines, scratches, or burn marks from the wheel. Good polish allows light to enter and exit cleanly. Polish and symmetry are both evaluated at 10× magnification.
Issued for all shapes
HOW THEY INTERACT (ROUND BRILLIANTS)
Highest possible combination — required for H&A designation
Very Good sym still qualifies for Excellent overall cut
Good sym typically caps overall cut at Very Good
Fair sym prevents Excellent or VG overall cut
Hearts & Arrows
Hearts & Arrows (H&A) is an optical phenomenon visible in precision-cut round brilliants when viewed through a special viewer. Looking down through the pavilion reveals eight symmetrical heart shapes; looking from above reveals eight arrow shapes.
Achieving a clean H&A pattern requires Excellent symmetry — the eight crown mains and eight pavilion mains must be precisely aligned in rotation. A single misaligned main facet breaks the pattern.
H&A is not a GIA grade — it is a descriptor used by some dealers and vendors. A GIA Triple-Excellent stone may or may not show a clean H&A pattern; the only way to verify is with a hearts & arrows scope or video inspection.
REQUIREMENT FOR H&A
HEARTS (PAVILION VIEW) · EXCELLENT SYMMETRY
Eight symmetrical hearts visible through a hearts & arrows scope. Requires Excellent symmetry — misalignment of even one main facet disrupts the pattern.
Buying guidance
Symmetry rarely needs to dominate a purchasing decision — but knowing where it matters and where it does not saves money.
ENGAGEMENT RING CENTRE (ROUND BRILLIANT)
The stone will be inspected closely and repeatedly. Triple Excellent (EX/EX/EX) is the premium target; EX cut / VG sym / EX polish is an excellent value option with no visible difference.
STEP CUT (EMERALD, ASSCHER)
Step cuts do not have a cut grade from GIA. Symmetry and polish are the only make grades available. A well-symmetrical step cut has even, parallel facet lines — very apparent in this style.
SIDE STONES / MELEE
Small accent stones are viewed in aggregate, not individually. Symmetry deviations are invisible at this scale. Good symmetry is perfectly appropriate.
HEARTS & ARROWS PURCHASE
If you are specifically paying for an H&A pattern, Excellent symmetry is mandatory. Verify with scope images or video — the GIA grade alone does not guarantee a clean pattern.
BUDGET-CONSCIOUS FANCY SHAPE
Ovals, cushions, and pears have no GIA cut grade. Good symmetry is fine for these — the shape itself has more visual variation than a round, making minor symmetry differences less perceptible.
INVESTMENT / RESALE
Triple Excellent rounds retain the most liquidity in the trade. Very Good symmetry slightly narrows the buyer pool for premium goods above 2 ct.