Lab Grown Diamonds
Heart Shapes: The Hardest Outline to Get Right
Symmetry is the whole shape, no laboratory grades it, and below a certain size it stops reading as a heart at all.
Written by the Mapple Gems workshop, Surat Β· Updated 4 October 2026
Short answer
Judge a heart on outline symmetry first β halve it down the centre and compare the lobes, the cleft and the shoulders, because asymmetry is the one flaw everyone notices and no report records. Aim for a length-to-width ratio near 1.00, and do not go below about 0.60Β ct: under that the cleft and point stop reading and it looks like a rounded triangle. It needs a V-prong on the point and prongs at both lobes, and it almost always needs a contour band.
Hearts are the shape most often bought on sentiment and least often assessed properly. They are also the hardest outline in the trade to cut well, which is why quality varies more here than anywhere else.
A heart is the only shape whose defining feature is a SILHOUETTE the eye already knows by heart β and that is why small asymmetries are visible here that would pass unnoticed on any other stone. With a round or a cushion, nobody has a mental template precise enough to catch a fraction of a millimetre. With a heart, everyone does: we recognise the form instantly and we notice immediately when one lobe sits higher, when the cleft is off-centre, or when one shoulder is fuller than the other. None of that appears anywhere on a grading report. Symmetry as graded by a laboratory refers to facet alignment, not to whether the outline looks right β and no laboratory grades cut on any fancy shape at all. So on a heart the buyer is doing the work that a cut grade does on a round, and doing it on the one shape where the human eye is most sensitive. The test costs nothing: view it face-up on a plain background, straight on, and mentally fold it down the middle. If the two halves do not match, no grade on the paperwork will make up for it, and no setting will hide it.
What to check, in order
| Feature | What good looks like |
|---|---|
| The two lobes | Same height, same fullness |
| The cleft | Centred, defined, not shallow |
| The point | Aligned with the cleft, not skewed |
| L:W ratio | 0.95 β 1.05 β derive it yourself |
| The bow-tie | Breaks up on tilt, in video |
| Girdle at the point | Not knife-thin β chip risk |
The ratio is never printed; divide length by width on the measurements line. Below about 0.90 a heart reads narrow and slightly severe; above 1.10 it starts looking squat. Near 1.00 is the classic, though a slightly wider heart reads more generous on the finger.
The size floor
The most useful practical rule, and the one that prevents most disappointment. Below roughly 0.60Β ct, a heart stops looking like a heart.
The cleft and the point are small features, and at small sizes they lose definition β the outline softens into a rounded triangle, which is exactly what people mean when they say a heart pendant βdoes not readβ from across a room. It is also why hearts work better as pendants and rings than as small earrings.
If the budget suits a smaller stone, a heart is the wrong shape rather than a compromise β a well-cut round or pear at the same weight will look better. Above about 1Β ct the shape has room to be itself.
Setting it
A heart has one point and two curved lobes, and each needs different treatment.
A V-prong on the point, always β the girdle runs thinnest there and an unprotected point is the commonest chip on this shape. Prongs at each lobe, positioned at the outer curve rather than at the top edge, which keeps them from sitting across the cleft and interrupting the outline.
Five prongs is the usual arrangement: one V at the point, two at the lobes, two at the sides. Watch for a design that puts metal across the cleft β it visually fills the notch that defines the shape and is the commonest setting error on hearts.
A half bezel is the wrong instinct here for the same reason it is wrong on an oval: it protects the sides and leaves the point open. If you want maximum protection, a full bezel or an end cap over the point is the answer.
Which grades matter
Clarity: eye-clean is the standard, and the plot is worth opening. The point and the lobe edges are where prongs go, so inclusions there are hidden; anything under the table is not.
Colour: hearts, like all brilliant-faceted fancy shapes, concentrate colour toward the point β so a warmer grade shows slightly more at the tip than in the body. In warm metal HβI is fine; in white gold or platinum stay at G or better.
Cut: ungraded, as on every fancy shape. Rotating video in ordinary indoor light, not a lightbox β and watch specifically for a dark band across the lobes that stays put through rotation, which is a pavilion cut for weight rather than light.
Band fit and wear
A heart extends along the finger and the point sits low, so a straight band usually gaps. Run the straight-edge test against the CAD side elevation before casting, and order any contour band with the ring rather than commissioning one later.
Two wear notes. The point is the lowest and most exposed part of the setting, so it catches first β a slightly lower profile helps considerably. And because the outline is asymmetrical front to back, a heart shows rotation more than any other shape: if the ring spins even slightly the stone visibly tilts. Ask for a euro shank, which is designed in, invisible from above, and needs no maintenance.
Keep reading
Frequently asked questions
How do I judge a heart shaped diamond?
Outline symmetry first β view it face-up on a plain background and mentally fold it down the middle, comparing the lobes, cleft and shoulders. It is the flaw everyone notices and it appears nowhere on a report, since laboratory symmetry grades facet alignment rather than outline.
What is the smallest heart shape worth buying?
About 0.60Β ct. Below that the cleft and point lose definition and the outline softens into a rounded triangle. If the budget suits a smaller stone, a heart is the wrong shape rather than a compromise β a round or pear at the same weight will look better.
How should a heart shaped stone be set?
A V-prong on the point, prongs at the outer curve of each lobe, and typically five in total. Avoid any design putting metal across the cleft, which fills the notch that defines the shape. A half bezel is wrong here β it protects the sides and leaves the point exposed.
What length-to-width ratio should a heart be?
Around 0.95β1.05, with 1.00 the classic. Below about 0.90 it reads narrow and severe; above 1.10 it looks squat. The ratio is never printed on a report β divide length by width on the measurements line yourself.
Ask for it face-up on a plain background.
On a heart that single photograph settles more than the whole report does.
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