A bow tie is not automatically a defect. A distracting bow tie is a reason to keep comparing.
What causes it
GIA describes the bow-tie effect as a darkened central region in elongated diamonds. It occurs when light obscured by the observer is directed into the center by the faceting arrangement.
| Bow-tie appearance | What it may look like | Our response |
|---|---|---|
| Minimal | Light contrast that appears and disappears in motion | Usually acceptable if the stone remains lively |
| Moderate | Clearly visible central band | Compare in several lights and distances |
| Strong | Broad, dark band dominating the center | Usually reject unless the client genuinely prefers the stone |
| Persistent | Remains dark through movement and lighting changes | Greater concern than a bow tie that breaks up in motion |
Why still images can mislead
A single photo freezes one lighting and viewing position. A bow tie should be judged as the diamond moves. Look for whether the dark area breaks into lively contrast or stays heavy and dead.
Length-to-width ratio is not the whole answer
More elongation can influence the appearance, but faceting and pavilion-angle variations matter too. Two ovals with the same ratio may show very different bow ties.
How to compare
View the stone from normal ring distance, not only inches from your face. Move it under diffuse light and spot light. Compare it beside another diamond of the same shape.
Contrast gives a diamond life. A dark stripe should not take over the performance.
Editorial basis includes GIA's 2025 oval guide, 2026 cut glossary and fancy-shape research.
What is the bow-tie effect?
It is a darkened region across the center of some elongated diamonds, often shaped like a bow tie.
Which shapes can show a bow tie?
Oval, pear and marquise diamonds commonly show it; some elongated cushions and radiants can also show central contrast.
Is every bow tie bad?
No. Some contrast is normal and can add dimension. The concern is a broad, dark or persistent band that dominates the diamond.
Can a grading report tell me how strong the bow tie is?
Usually not in a way that replaces viewing. Videos and direct side-by-side comparison are more useful.
Does a bow tie disappear once set?
The appearance can change with setting and lighting, but a strong bow tie does not reliably vanish after mounting.