Are you shopping for an oval diamond engagement ring and noticing a dark band across the centre of some stones? This is called the bow-tie effect. It can be subtle and shifting, or pronounced enough to draw your eye constantly. Should you avoid it at all costs? Not necessarily: a little contrast contributes to a diamond’s visual character. The goal is to choose a stone whose centre stays lively as it moves. Here is how to tell the difference before buying in Montréal or elsewhere in Québec.
The bow-tie effect comes from the way light behaves within a diamond’s facets. Depending on their angles, certain areas return less light to your eye, particularly when your head or the camera blocks some of the lighting. Two dark areas can then form a bow tie across the middle of the stone. This is not an inclusion, a crack or dirt. The phenomenon mainly affects certain elongated shapes, including oval, pear and marquise. It can appear in both natural and laboratory-grown diamonds.
The right criterion is therefore not the complete absence of shadows in a photo. Instead, look at whether the central area alternates between contrast and flashes of light as the diamond tilts gently. A very dark band that remains dominant from several angles deserves closer attention, especially if it seems to divide the stone visually in two. By contrast, a passing shadow is not automatically a problem. Examine the diamond from about 30 to 40 cm away, then closer up: its appearance at a normal viewing distance, not just under magnification, is what will matter every day.
When buying remotely, ask for a 10- to 20-second video showing the stone tilting slowly, rather than a single flattering image. Ideally, view it in at least two settings: diffused light near a window, without direct sunlight, and ordinary indoor lighting. Small spotlights can create plenty of sparkle without clearly revealing the centre’s overall appearance. Also ask for a face-up view and side-to-side movements. A video helps with comparisons, but the camera’s position also affects the dark areas: no single image is enough to reach a conclusion.
The length-to-width ratio tells you about the outline, not the guaranteed intensity of the bow tie. A diamond measuring 9.0 mm by 6.0 mm has a ratio of 1.50, calculated by dividing its length by its width. As a reference, an oval with a ratio of 1.35 generally looks rounder than one with a ratio of 1.50. However, there is no magic ratio that eliminates this effect. Two stones with similar dimensions can respond very differently to light. First choose an outline you like, then compare each diamond’s visual performance.
A GIA or IGI report does not replace this observation. It documents the diamond’s identity and characteristics, among other things, but does not provide a universal bow-tie grade. Even excellent polish and symmetry ratings do not guarantee a shadow-free centre. Depending on the laboratory and report type, cut information can also vary. To make your choice, pair the report with images of the exact diamond being offered. Do not assume that higher clarity or a better colour grade will correct this optical effect: these are different criteria.
The setting can influence lighting and how the diamond is perceived, but it does not correct the angles of its facets. Avoid relying on a halo or a particular setting style to make a pronounced bow tie disappear. Before confirming your choice, compare three stones under similar conditions, along with their dimensions in millimetres, weight and price. A slightly lighter stone with a more visually balanced appearance may appeal to you more. A 3D rendering helps confirm the jewellery’s proportions; it cannot faithfully show this effect in the actual diamond.
At AUCLAIRE, a family-owned jewellery house in Montréal, centre diamonds are GIA- or IGI-certified, and every piece comes with an AUCLAIRE certificate of authenticity. A 3D rendering precedes production, which takes 3 to 4 weeks in Montréal. To move forward without getting lost in technical specifications, you can ask the atelier for three certified oval diamond options based on your budget and preferred outline. Mention that you would like to compare their bow-tie effects: this will help you discuss the contrast you enjoy and make an informed choice.
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