A bow tie is the dark band you can see across the middle of many oval, pear and marquise diamonds, and it is not a flaw in the gemmological sense. A GIA study published in Gems & Gemology (Fall 2024) found that the elongation of these shapes "tends to produce a bow tie" for most faceting arrangements, and that people disagree on whether a softer one spoils the stone or adds character.
That framing differs from much of what you will read online, where the bow tie is often presented as a cutting fault. Both views are worth understanding before you choose a stone.
What is the bow tie effect?
Looking down through the table of an elongated diamond, you may see a darker, roughly bow tie shaped area running across the width of the stone. GIA describes it as an area of dark contrast that can range from slight to thick, and that can be broken into segments or form one continuous dark bar.
GIA links it to the viewer's own reflection inside the stone, the same kind of reflection that creates the hearts and arrows pattern in some round diamonds. Observers who like that pattern in rounds, GIA noticed, often dislike it when it appears as a bow tie in these shapes.
Which shapes show it?
The GIA research looked at ovals, pears and marquise shapes, which it groups as rounded fancy shapes. Many retailers also mention hearts, and other elongated cuts can show a similar effect, but those were outside the scope of the study. Our guides to oval cut diamonds, pear shaped diamonds and marquise engagement rings cover each shape more broadly.
Is a bow tie a flaw?
This is where sources part ways. Plenty of trade pages describe a visible bow tie as a sign that a stone was cut poorly, and advise buyers to avoid it.
GIA's research is more nuanced. Its observers, drawn from diamond buyers, sellers, cutters and appraisers in several countries, generally disliked bow ties that were broad, dark or persistent. As the bow tie became narrower, less intense or lighter with movement, opinions diverged. In GIA's words, "some observers expect a bow tie pattern in these shapes", while others prefer very little or none. The study also found differences between regions, so taste plays a real part.
A fair summary is that a heavy, dark bow tie is widely seen as a negative, while a light one is largely a matter of preference.
Does it change when the diamond moves?
It can. GIA notes that some bow ties stay put, while others brighten as the diamond moves. That matters because a ring is rarely still on the hand. A stone that looks dark in a single still photograph may look livelier in person, and the reverse is possible too.
What affects how strong it is?
According to GIA, the faceting arrangement and proportions can accentuate or diminish a bow tie. Pavilion main facets running across the width of the stone, at its belly, often enhance it. GIA also reports that ovals submitted to its laboratory have shifted over time towards arrangements without belly mains, which reduce the bow tie.
Because so many parameters shape a fancy diamond, GIA argues that simple proportion charts cannot predict appearance reliably for these shapes. Our guide to cut grades for fancy shape diamonds explains how cut is assessed beyond the round brilliant.
How to look at a bow tie yourself
- View the stone moving, not only in a still image, since some bow ties lighten with motion.
- Look at it from a normal viewing distance, as you would see it on your hand.
- Compare two or three stones of the same shape side by side where you can.
- Ask yourself whether the dark area draws your eye first. If it does not, it may matter less than a chart suggests.
If you are considering an oval, browse our oval engagement rings for ideas, each crafted by specialist goldsmiths to your brief.
Frequently asked questions
Is a bow tie in a diamond a flaw?
Not in the sense of a clarity feature. GIA research found that elongated shapes tend to produce one, and that observers disliked broad, dark or persistent bow ties but disagreed about lighter ones. Many trade pages treat any visible bow tie as a cutting fault.
Which diamond shapes have a bow tie?
GIA studied oval, pear and marquise shapes and found the bow tie is part of their typical pattern. Many retailers also mention heart shapes.
Does the bow tie change when the diamond moves?
For some stones, yes. GIA notes that some bow ties are persistent while others brighten as the diamond moves.
Can the cut reduce a bow tie?
The faceting arrangement and proportions can accentuate or diminish it. GIA found that pavilion main facets across the belly of the stone often enhance a bow tie.
Is a bow tie shown on a grading report?
We have not found a grading report that records it as a separate item, so the best way to judge it is to see the stone itself or a video of it moving.