Cut registry › Jewellery cuts › Oval
Jewellery cuts · Elongated brilliant
The round brilliant, stretched.
An oval is a round brilliant’s faceting poured into a longer outline. Almost everything people worry about when buying one follows from that single decision.
The short version
An oval cut diamond is an elongated brilliant with a rounded, symmetrical outline and the same brilliant-style faceting as a round diamond, typically 56 to 58 facets.
Its defining measurement is its length-to-width ratio, which sets how long the stone reads on the hand and, together with its proportions, how visible its bow-tie is.
Definition
The oval takes the round brilliant’s facet plan and stretches it. The crown still carries a table, stars, bezels and upper girdle facets; the pavilion still carries mains and lower girdles. Only the outline changes, from a circle to an ellipse.
That is why an oval behaves like a round in some ways and not at all in others. The facet families are the same, so the character of the sparkle is familiar. The symmetry is not, because an ellipse has two axes rather than infinite rotational symmetry, and the light no longer arrives at every facet on equal terms.
The shape is usually credited to Lazare Kaplan, who developed the modern oval brilliant in the late 1950s. It is now the most widely bought fancy shape, chosen for the way it lengthens the finger and for reading larger face-up than a round of the same weight.
Proportions
The ranges below are what the trade commonly cites. The right-hand column is the reference oval we measure on the Index, so you can see exactly which stone every figure on this page describes.
| Measure | Commonly cited | Our reference stone | What it does |
|---|---|---|---|
| Length-to-width | 1.30 to 1.50 | 1.33 | Sets how long the stone reads. An aesthetic choice, within limits. |
| Depth | 58% to 62% | 64.0% | Too shallow and light passes through; too deep and it hides weight below the table. |
| Table | 53% to 63% | 54.7% | The flat top, as a share of the width. |
| Pavilion angle | not commonly published | 35.9° | The angle that decides whether light reflects back or escapes. |
| Facets | 56 to 58 | 93 | Counted as facets that actually reach the surface. |
GIA issues no cut-quality grade for ovals, or for any fancy shape. Symmetry and polish are graded; cut is not. That absence is the reason proportion ranges carry so much weight in oval buying advice, and the reason we measure the shape ourselves.
The bow-tie
A bow-tie is a dark band lying across the waist of an elongated brilliant. It is a shadow rather than a fault: the facets beneath it draw their light from the part of the sky that your own head and shoulders are blocking as you look down at the stone.
That distinction decides what you can do about it. Light leakage is a failure of the pavilion angles, it is present under any light, and it shows on a light-return map. A bow-tie only appears when something is standing in the way of the light, which is why it darkens and lifts as you move your hand. A good deal of published advice calls the bow-tie a leak. It is not, and the two want different remedies.
Some central contrast is inherent to the shape, and we will not pretend otherwise. GIA describes the mechanism plainly: the band darkens as the difference between length and width grows, and as variation in the pavilion angle becomes more extreme. A well-cut stone reduces it. Nothing eliminates it.
What we can and cannot measure. Our engine illuminates from a narrow overhead cone and contains no observer, so by construction it cannot cast a head shadow, and our reference geometry for this shape carries no twist in the pavilion mains. We tested for a bow-tie twice, once under the standard face-up cone and once under full-hemisphere light with a modelled observer blocking the central 25°, and found none in either run while the round-brilliant control behaved exactly as it should. So we do not publish a bow-tie severity figure for this cut. We would rather leave the column empty than fill it with a number we cannot stand behind.
What we measured instead. Ratio is treated as the great unresolved question of oval buying. It is not, at least not optically. Taking the oval’s own facet plan and stretching it across the range people actually shop, from 1.30 to 1.70, the Global score moves inside a band of about two points and does not move in one direction. Differences that small sit inside the engine’s own resolution. Choose the ratio you like the look of. The optics are not going to settle it for you.
Light
Every figure here comes from the same census that measures the house cuts and the historic cuts on this site: 3,200 rays face-up, 2,200 more at a 20° tilt, on exact facet geometry. The standard is T57, Tolkowsky’s 1919 round brilliant.
| Material | Useful light | Leak | Fire | Scintillation | Global | vs the standard |
|---|---|---|---|---|---|---|
| Diamond | 46.85% | 26.99% | 92.46 | 87.34 | 74.96 | −13.65 |
| Moissanite | 38.36% | 33.11% | 95.40 | 87.34 | 72.89 | −16.93 |
| Cubic zirconia | 63.47% | 18.93% | 96.26 | 87.34 | 79.81 | −11.96 |
| T57 standard, diamond | 92.28% | 1.88% | 78.85 | 71.82 | 88.61 | 0.00 |
Our reference oval returns 46.85% of the light entering it usefully, against the round brilliant’s 92.28%, and leaks 26.99% against 1.88%. That is the price of the outline, and it is a large price. An oval is bought for its shape, not for its light return, and the honest version of this page says so.
It wins the terms that reward facet count and movement. At 93 active facets it scores 87.34 on scintillation against the standard’s 71.82, and its fire reads 92.46 against 78.85. An oval throws more separate flashes and more colour than a round brilliant does. It simply sends less of the light back.
The result is 74.96 Global against 88.61, a gap of 13.65 points. Among the twenty-one jewellery cuts we measure, that places the oval twelfth.
Where the light is: useful return along the length
Every returning ray binned by the point on the crown it leaves through, in five equal bands from one end to the other. The belly returns 83.1% and the ends 41.9%, a spread of 41.2 points. The same measurement on the round brilliant control reads 99.1% against 98.1%, a spread of 1.0. The light in an elongated brilliant lives in the middle of the stone, and this is how far from evenly it is spread.
Against the standard
Light return. The round brilliant wins, and not narrowly. 92.28% against 46.85% of useful light, on identical protocol. Nothing about an oval’s geometry lets it close that gap, because the gap is the geometry.
Sparkle character. The oval carries 93 facets to the standard’s 57, so it produces a finer, busier flash pattern and more dispersed colour. Whether that reads as better is a matter of taste, and we will not pretend a number settles it.
Face-up size. An oval commonly looks larger than a round of the same carat weight, because the same weight is spread across a longer outline. We do not put an Index figure on this: our spread axis is derived from depth alone and does not model the outline, so quoting it here would be quoting the wrong measurement.
Durability. An oval has no points and no corners. Among the fancy shapes it is one of the safest for daily wear, which is a genuine advantage over the pear and the marquise.
Price. Ovals generally cost less per carat than rounds of comparable quality, because less of the rough is lost in cutting one.
The baseline for all of this is the round brilliant itself. Its facet plan is set out in the anatomy of a round brilliant, and the measured standard we compare against is T57, the stone Tolkowsky published in 1919.
Materials
In moissanite the oval returns 38.36% of entering light and scores 72.89 Global. Moissanite’s higher refractive index of 2.65 wants a shallower pavilion than diamond does, so a facet plan drawn for diamond leaks more in it: 33.11% here. What it buys is fire, which reads 95.40 against 92.46 in diamond.
In cubic zirconia the same outline returns 63.47% and scores 79.81. Zirconia’s index of 2.16 sits below diamond’s, which changes the critical angle again and, on this geometry, suits it better than diamond does.
The point is not that one material is best. It is that a facet plan is drawn for one refractive index, and moving the same plan into another material changes where the light goes. You can watch that happen for this shape in the Index.
Trade-offs
Questions
The questions buyers actually ask, answered in full. Where the answer is ours to prove, the figure is measured on the Index; where it is an established gemological fact, it is stated as one.
An oval cut diamond is an elongated brilliant: a round brilliant’s facet plan, typically 56 to 58 facets, applied to an elliptical outline. It keeps the round’s facet families, including stars, bezels, mains and girdle facets, and changes only the shape of the girdle. The modern oval brilliant is usually credited to Lazare Kaplan in the late 1950s.
Nearly all elongated brilliants show some bow-tie, and it is a shadow rather than a leak. The dark band appears because the facets across the waist draw their light from the region of sky that the viewer’s own head and shoulders block. GIA describes it as darkening when the difference between length and width increases, and when variation in the pavilion angle becomes more extreme. Good cutting reduces it; nothing removes it.
The commonly cited range is 1.30 to 1.50, and many buyers narrow that to 1.35 to 1.50. Optically it matters far less than that advice implies: stretching the oval’s own facet plan from 1.30 to 1.70 on our engine moves its Global score inside a band of about two points, and not in a single direction. Choose the ratio on how it looks on the hand.
The trade commonly cites 58% to 62% depth and 53% to 63% table. Outside those ranges light return falls away in both directions: too shallow and light passes straight through the pavilion, too deep and weight is buried below the table where it does nothing for face-up size. Our reference oval sits at 64.0% depth and 54.7% table.
Usually yes, because the same weight is spread across a longer outline, so more of the stone faces up. We do not attach an Index figure to this claim: the spread axis on our engine is derived from depth alone and does not model the outline, so it is the wrong measurement to quote here. Compare face-up millimetres rather than carat weight.
Typically 56 to 58, the same families as a round brilliant. Our reference oval measures 93 facets that actually reach the surface, which is the count our scintillation figure is built on.
No. GIA issues cut grades for round brilliants only. An oval’s report will carry symmetry and polish grades, which describe finish rather than light performance. That gap is why proportions and independent measurement matter more for an oval than for a round.
Generally yes, per carat, for comparable colour and clarity. Cutting an oval wastes less of the original rough than cutting a round does, and that saving reaches the price. The size of the discount moves with the market, so treat any fixed percentage with suspicion.
Look for an even curve with no flat spots along the sides, shoulders that match, and a bow-tie that lifts as you move the stone rather than sitting as a permanent dark block. Then look at how the light is distributed along the length: on our reference oval the belly returns 83.1% against 41.9% at the ends, and a well-cut stone keeps the ends alive rather than dead.
Yes. An oval has no points and no sharp corners, which makes it one of the more forgiving fancy shapes for daily wear. It needs no special protective setting, unlike a pear, marquise or princess.
Next
See the whole set on the jewellery cuts index, or the measured house and historic cuts in the cut registry.
Method
Monte-Carlo on exact facet geometry: 3,200 rays face-up plus 2,200 at 20° tilt, cosine-weighted from a 7° near-vertical cone. Useful light is what exits through the crown within 64° of vertical. The same protocol runs on every cut on this site, so the figures are comparable to each other.
They measure our reference geometry for the shape at the proportions listed above, not an average of stones on the market. A oval cut to different proportions will read differently. Treat them as a like-for-like comparison between shapes, not as a grade for any individual stone.
Engine estimates, ±2 points, not lab-certified grades. We do not publish the Index symmetry axis on these pages: it scores facet regularity within each pavilion family, which is meaningful for a round brilliant and misleading for a shape whose pavilion is deliberately irregular.
87.34 here against the standard’s 71.82. The term is 100(1−e−n/45) on the count of facets that actually reach the surface, so it is a pure function of facet count and nothing else.