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Education›Lab Grown Diamond Guidance›What is the Diamond Bow Tie Effect?

Lab Grown Diamond GuidanceFenora Guide8 min read

What is the diamond bow tie effect?

The bow tie effect is a dark shadow across the middle of certain fancy-shaped diamonds — most visible in oval, pear and marquise cuts. Every elongated brilliant-cut diamond has some degree of bow tie; the question is severity. This guide explains what causes it, how to assess it and how to avoid a problematic bow tie.

What the bow tie effect is — the cause

The bow tie effect is a dark, bow-tie shaped shadow visible across the width of certain fancy-shaped diamonds — typically oval, pear, marquise and elongated cushion cuts. It is named for its resemblance to a bow tie or butterfly shape.

The cause is optical. In elongated brilliant cuts, the central area of the diamond is at an angle to the observer's line of sight that causes light to be directed away from the eye rather than toward it. The observer's head and body block some of the light that would normally enter from above, creating a shadow in the central area of the stone.

The bow tie effect is inherent to the geometry of elongated brilliant cuts — every oval, pear and marquise diamond has some degree of bow tie. The question is not whether bow tie exists but how severe it is. A very faint bow tie is invisible in most lighting conditions. A strong bow tie is the dominant visual feature of the stone and significantly reduces its beauty.

“Every elongated brilliant cut has some bow tie. The question is always: how strong? A faint bow tie in a well-cut oval is not a compromise — it is a normal characteristic of the shape. A strong bow tie in a poorly cut stone is a different matter entirely.”
— Yash Chandpara, Founder

Bow tie severity — from invisible to dominant

Severity	Description	Visible In	Effect on the Stone
Very Faint / Invisible	No visible shadow in any normal lighting	Not visible	No practical effect. The stone performs excellently
Faint	Slight shadow visible only in specific conditions (very bright directional light)	Occasionally in strong sun or under bright spot lighting	Minimal — does not distract from the stone beauty
Moderate	Shadow clearly visible in bright light. Not dominant in diffuse light	In strong lighting and sunlight	Noticeable but not the defining characteristic
Strong	Prominent shadow visible in most lighting conditions	In most lighting, including diffuse indoor light	Significantly reduces the apparent brilliance of the central area
Very Strong	The bow tie dominates the stone in all conditions	In all lighting	The primary visual feature of the stone — dramatically reduces appeal

Which shapes are affected — and which are not

Affected — always assess in video

Oval brilliant — the most common shape with bow tie. Every oval has some degree
Pear — bow tie visible in the central area between the rounded base and the pointed tip
Marquise — bow tie across the widest central area
Elongated cushion — bow tie possible in the elongated central area

Not affected — no bow tie

Round brilliant — the symmetrical circular outline eliminates the bow tie phenomenon
Emerald cut — step cut faceting does not create the bow tie effect (different optical characteristics)
Asscher — same as emerald
Princess — square outline eliminates elongated bow tie geometry
Round Portuguese — symmetrical, no bow tie

How to assess bow tie before purchase — the only reliable method

Bow tie cannot be reliably assessed from a photograph — photos are taken in controlled conditions, from fixed angles, with specific lighting chosen to minimise shadow effects. The only reliable assessment method is video under multiple lighting conditions.

01
Request video of the stone rotating under controlled lighting
This is standard practice at Fenora for all oval, pear, marquise and elongated cushion stones. The rotation shows the bow tie from multiple angles under both diffuse and directional light.
02
Assess in multiple lighting conditions
A bow tie that disappears in diffuse light is faint or very faint — not a concern. A bow tie that remains visible in diffuse indoor light is moderate to strong — assess whether it is acceptable.
03
Look specifically at the centre of the stone
The bow tie occupies the central width of the stone. In the video, focus on the area between the widest points — this is where the shadow appears.
04
Compare with a reference
Ask Yash Chandpara to show a reference stone with a good cut alongside the stone being assessed. The comparison makes bow tie severity immediately clear.

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Questions about bow tie or fancy cut diamonds? Ask Yash Chandpara.

Book a free online consultation. Yash Chandpara shows every oval, pear and marquise stone in video under multiple lighting conditions — the bow tie severity is immediately clear.

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