Lab-Grown Oval Diamonds Without Bow Tie: How Ouros Jewels Selects Its Stones

Every Oval Has a Bow Tie — The Question Is How Bad

Oval diamonds are among the most searched engagement ring shapes in 2026, and for good reason. They face up larger than rounds of the same carat weight, they flatter the finger, and they carry a quiet elegance that suits both vintage and modern settings. But almost every oval diamond — lab-grown or mined — carries a shadow across its center called the bow-tie effect.

The bow tie is not an inclusion. It is not a flaw you can see on a grading report. It is a dark, horizontal band across the center of the stone that appears when light does not reflect evenly back through the facets. The shadow tends to look like two triangles pointing toward each other — hence the name. In a poorly cut stone, it reads as a thick black stripe that kills the stone’s brilliance. In a well-cut stone, it either disappears under most lighting conditions or softens into a faint contrast that actually adds depth.

So the real question when shopping for an oval is never “does this diamond have a bow tie?” Almost all of them do. The question is whether the bow tie is subtle enough to be invisible in everyday wear, or prominent enough to be the first thing you notice when the ring catches light.

Why the Bow Tie Happens — and Why Lab-Grown Ovals Are Not Immune

The physics behind the bow tie is straightforward. When you look at an oval diamond face-up, your head partially blocks the light that would otherwise enter the stone from above. Because of the angles of the pavilion facets in an elongated shape, that light blockage creates a shadow across the center. Round brilliant diamonds avoid this entirely because their symmetrical facet pattern distributes light evenly in all directions. Ovals, pears, and marquise cuts are all susceptible because their elongated geometry means the center facets work differently from the pointed ends.

Lab-grown oval diamonds behave identically to mined ovals in this regard. Whether a stone was grown via CVD or HPHT makes no difference to its optical performance — the bow tie is entirely a function of cut quality and proportions, not origin. A poorly proportioned lab-grown oval will show the same dark band as a poorly cut mined stone. A well-cut lab-grown oval will perform just as cleanly.

The challenge is that GIA does not issue an overall cut grade for fancy shapes like ovals. They assess polish and symmetry, but there is no single “Excellent cut” stamp that tells you the bow tie is minimal. IGI moved closer to addressing this in late 2022 when it began including cut grades for fancy-shaped loose diamonds — a system that incorporates shape-specific considerations for ovals, pears, and marquise cuts. Even so, IGI does not grade bow-tie severity as a standalone metric. This means the certificate alone will never fully tell you what you need to know. You have to look at the stone.

The Proportions That Matter Most

When evaluating an oval for bow-tie risk, three proportions are the starting point.

Length-to-width ratio is the most discussed. A ratio between 1.35 and 1.50 tends to produce ovals that balance elegance with light performance. Ratios in the 1.40–1.45 range are the most popular because they offer strong finger coverage without the stone looking too narrow or too round. Extremely elongated ovals — ratios above 1.55 — are more likely to show a pronounced bow tie because the center facets have to cover a longer, narrower span.

Depth percentage matters because a stone that is too shallow will leak light through the pavilion rather than reflecting it back up through the table. A stone that is too deep will trap light in the lower half of the stone. For ovals, a depth percentage in the 58–68% range generally produces the best light return. Stones outside that window — particularly those cut shallow to maximize face-up size from a piece of rough — are where bow ties tend to get worse.

Pavilion angle consistency is the factor most buyers never think to ask about. The pavilion is the lower half of the diamond, and its facets are what control how light bounces back to your eye. If the pavilion facets are cut at inconsistent angles — even a variation of 0.3 degrees from optimal — the result is uneven light distribution and a more visible bow tie. More facets in the center area of the pavilion generally help, because more reflective surfaces mean more light bouncing back through the middle of the stone.

None of these numbers appear on a standard certificate. They require either a direct measurement or a trained eye reviewing actual video of the stone.

How Ouros Jewels Approaches Stone Selection

At Ouros Jewels, the process of selecting oval lab-grown diamonds for its engagement ring collection is not automated. Each oval is reviewed individually before it is offered to a customer.

The first filter is proportional: stones are evaluated against the length-to-width and depth ranges known to minimize bow-tie risk. Ovals that fall outside the 1.35–1.50 ratio window, or that have depth percentages outside the optimal range, are flagged. This eliminates a significant portion of the available supply before any visual evaluation begins.

The second filter is visual. Every oval candidate is reviewed in high-definition video under multiple lighting conditions — not just the single bright-light setup that makes most diamonds look their best. The goal is to identify stones where the bow tie either disappears under normal lighting or reduces to a faint gray contrast that adds depth rather than deadening the center. Stones where a dark, fixed shadow remains visible from most angles are not selected.

For IGI-certified stones at 1.00 carat and above, Ouros Jewels requires that the polish and symmetry grades meet Excellent or Very Good standards. Symmetry is particularly relevant here: an oval with poor symmetry will often show an asymmetric bow tie — darker on one side than the other — which is more visually disruptive than a centered, even shadow.

The result is that the oval lab-grown diamond engagement rings in the Ouros Jewels catalog are sourced with bow-tie minimization built into the selection criteria, not treated as an afterthought. Customers choosing from 0.25 carat up to 5 carat oval center stones benefit from this pre-screening process.

What You Should Do When Buying Any Oval Diamond

Whether you buy from Ouros Jewels or anywhere else, the following approach will serve you well.

Request 360-degree video, not just photos. A still image in bright lighting can hide a severe bow tie entirely. Video shows you how the stone behaves as it moves through different angles and lighting conditions. A well-cut oval will maintain even brightness across the center as it rotates. A stone with a problematic bow tie will show a dark, fixed band that stays visible regardless of the angle.

Check the proportions before you fall in love with the size. A 2-carat oval that has been cut shallow to maximize face-up spread may look impressive in a photo but perform poorly in real light. Compare depth percentages across stones of similar carat weight and shape.

Understand what “subtle” means. A faint bow tie — one that appears only at certain angles or in direct overhead light — is normal and not a quality problem. Some buyers even prefer a slight bow tie because it creates contrast that makes the rest of the stone appear brighter by comparison. What you are trying to avoid is a thick, dark band that is visible in most lighting conditions and from most viewing angles.

Ask for symmetry and polish grades, not just color and clarity. For oval diamonds, Excellent or Very Good symmetry is the closest proxy available on a certificate for cut quality. It does not guarantee a clean bow tie, but poor symmetry almost always correlates with a more visible one.

And if you are working with a jeweler who cannot provide video of the actual stone you are purchasing — or who cannot tell you the depth percentage and length-to-width ratio — that is worth noting before you commit. An oval diamond is one of the shapes where the certificate tells you the least about how the stone actually looks.