SHAPE ELONGATED BRILLIANTS OPTICAL PHENOMENON

Bow-tie effect

A dark shadow band across the centre of elongated brilliant-cut diamonds — ovals, pears, marquises and hearts. All elongated shapes show some bow-tie; severity is what matters.

When you look down at an oval or pear from above, your head blocks some of the light that would otherwise enter the stone from directly above. The pavilion facets in the centre of the stone — those oriented perpendicular to its length — reflect this shadow back at you as a dark band. Because it resembles two triangular wings joined at the centre, it's called a bow-tie.

Every elongated brilliant has at least a trace of this effect. It is a physical consequence of the shape, not a defect or grading factor. The relevant question is not whether it exists, but how severe it is — and that can only be assessed by looking at the stone, not by reading the grading report.

A subtle bow-tie is harmless and can actually add depth and contrast to the stone's appearance. A severe bow-tie dominates the face-up view and makes the stone look dark and lifeless in most lighting conditions.

AFFECTS: Oval, Pear, Marquise, Heart
ON REPORT: Not graded
IDEAL: Subtle

SHOWCASE · FACE-UP VIEW · OVAL Subtle

None

An extremely well-cut oval or pear with no visible bow-tie. Very rare — most elongated stones show at least a trace. Often achieved at the cost of a slightly less optimal length-to-width ratio.

Visibility: Not visible
Buyer verdict: Very rare, may look flat
On grading report: Not mentioned

Extremely rare in practice. May indicate the stone was cut to minimise bow-tie rather than maximise brilliance.

Subtle

A faint darkening across the centre that is visible only under certain lighting angles. Does not affect the overall appearance in normal conditions. Considered ideal — a stone with zero bow-tie can sometimes look glassy.

Visibility: Certain angles only
Buyer verdict: Ideal
On grading report: Not mentioned

The sweet spot for most buyers. Barely perceptible face-up, adds depth and contrast to the stone.

Moderate

Clearly visible in most lighting conditions but does not dominate the face-up appearance. The rest of the stone still shows good brilliance. Acceptable at a discount; worth examining in person.

Visibility: Most lighting
Buyer verdict: Acceptable with discount
On grading report: Not mentioned

Visible in photos. The bow-tie is defined but not distracting when the stone is set.

Severe

A prominent dark band that dominates the face-up view and significantly reduces the apparent brilliance of the stone. Caused by very poor pavilion angle optimisation. Avoid.

Visibility: All conditions
Buyer verdict: Avoid
On grading report: Not mentioned

Dominates the face-up appearance. Indicates poor cut proportions — the stone will look dark and lifeless in most lighting.

Why it happens

Light enters a diamond from above. When a viewer looks down at the stone, their head and body cast a shadow — blocking a cone of light from directly above. In a round brilliant, the perfectly symmetric facet arrangement distributes this shadow so evenly it becomes invisible.

In an elongated shape, the pavilion facets at the widest central zone are oriented at angles that reflect this overhead shadow directly back to the viewer's eye. The longer and narrower the stone, the more extreme the angles, and the more prominent the bow-tie.

Cutters can minimise the effect by adjusting the pavilion angles in the central zone — but there are limits. Some bow-tie is inherent to any elongated brilliant; eliminating it entirely requires proportions that trade other optical qualities.

Light enters from above

The diamond is illuminated from above and all sides. The viewer's eye is positioned above the table.

Viewer's head blocks overhead light

A cone of light directly above is blocked. In a round, this shadow is diffused by symmetric facets.

Central facets reflect the shadow

The pavilion facets in the elongated centre zone bounce the blocked-light cone directly back to the eye — appearing dark.

Result: dark band at centre

Two triangular dark zones meet at the centre of the stone, forming the characteristic bow-tie silhouette.

Which shapes are affected

Bow-tie appears in elongated brilliant-cut shapes. Step cuts and round brilliants are not affected.

Oval

Bow-tie possible

Typical: Subtle–Moderate

Most common shape with bow-tie. Severity depends heavily on L:W ratio and pavilion angles.

Pear

Bow-tie possible

Typical: Subtle–Moderate

Bow-tie appears in the wide body. Also look for uneven shoulders and a pinched neck.

Marquise

Bow-tie possible

Typical: Subtle–Severe

Often shows stronger bow-tie than oval due to the more extreme elongation and pointed ends.

Heart

Bow-tie possible

Typical: Subtle–Moderate

Bow-tie appears in the lower half. Symmetry of the two lobes is also important to evaluate.

Round

Not affected

Perfect radial symmetry distributes shadows evenly. No bow-tie possible.

Emerald

Not affected

Step cut — no pavilion wedges to create the bow-tie pattern.

Princess

Not affected

Square brilliant — symmetric, no elongated central zone.

Cushion

Not affected

Square/slightly elongated but cushion faceting distributes shadows differently.

How to evaluate bow-tie

Because the bow-tie is not on the grading report, you must assess it yourself. Here is what to look for.

Watch a video, not just photos

A still photograph under a single directional light source can hide or exaggerate a bow-tie. A 360° rotating video under natural or mixed lighting reveals how the stone behaves as you move it.

Check multiple lighting conditions

Look at the stone under spot lighting (a ceiling light), diffuse lighting (overcast sky / window light), and mixed. Bow-tie is most visible under diffuse lighting; spot lighting can make even a severe stone look acceptable.

Assess face-up, not at an angle

The bow-tie is most pronounced when you look straight down at the table. Tilting the stone at an angle will often make it disappear. Grade it face-up — that's how the stone will look 90% of the time in a setting.

Compare the bow-tie zone to the wings

A well-cut oval should have brilliant, lively wings on either side of the bow-tie. If the whole stone looks dark, the issue is cut quality overall, not just bow-tie.

Check the length-to-width ratio

More elongated stones (L:W > 1.50) tend to show stronger bow-ties. The sweet spot for ovals is typically 1.30–1.45. Marquises can go higher (1.75–2.25) but require especially careful pavilion angle optimisation.

HOW FACET HANDLES BOW-TIE

DiamondTheGuide's price benchmarks for ovals, pears and marquises include all stones at the selected specification regardless of bow-tie severity, because it is not a graded or reported characteristic. The explorer shows depth % and table % for each stone, which are indirect indicators — very deep or very shallow pavilions often correlate with more severe bow-ties. Viewing the actual stone video remains the only reliable way to assess bow-tie before buying.

RELATED TERMS

Questions about the bow-tie effect

Is a bow-tie always bad?

No. A subtle bow-tie is considered normal and even desirable by many buyers and cutters — it adds contrast and depth that makes the stone look more dynamic. A stone with zero bow-tie can appear glassy or flat under diffuse lighting. The issue is severity: a moderate bow-tie is a trade-off worth understanding; a severe bow-tie significantly reduces the beauty of the stone.

Which shapes get a bow-tie?

Any elongated brilliant-cut shape can show a bow-tie: oval, pear (teardrop), marquise, and heart. It does not appear in round brilliants (symmetric), princess cuts (square), or step cuts like emerald and Asscher. The bow-tie is a direct consequence of the elongated outline interacting with the pavilion facet angles.

Can I judge bow-tie severity from a grading report?

No. GIA and IGI grading reports do not mention bow-tie effect. It is not a clarity or cut grade factor for fancy shapes, because GIA does not issue cut grades for fancy shapes at all. Bow-tie must be evaluated by looking at the stone — ideally in video or in person under different lighting conditions. Some retailers show rotating videos specifically to reveal bow-tie.

What causes the bow-tie?

When light enters an elongated brilliant from above, the viewer's shadow falls across the pavilion facets oriented perpendicular to the length of the stone. Those facets reflect the observer back at them — a dark zone rather than returning light. The more extreme the elongation and the steeper the pavilion facets in that zone, the darker and wider the bow-tie appears.

Can a bow-tie be fixed?

Sometimes. A cutter can adjust pavilion angles in the central zone to redirect light, but this usually requires re-cutting the stone, which reduces carat weight and costs money. For most buyers, it is better to select a stone with an acceptable bow-tie from the outset rather than paying for rework.

Does the bow-tie affect price?

Indirectly, yes. There is no formal bow-tie grade that appears in pricing tables. However, stones with severe bow-ties sell at a discount because they are harder to sell — experienced buyers know to avoid them. Asking price medians for ovals and pears in DiamondTheGuide include stones across the bow-tie spectrum, so the benchmark price may overstate what a visually superior stone would cost.