What is the bowtie effect in oval diamonds?

The bowtie is a dark shadow that appears across the middle of oval diamonds when viewed face-up. All ovals have some bowtie; a faint one is acceptable, but a severe bowtie diminishes the stone's appearance. It cannot be assessed from a certificate and must be viewed in person.

Why do oval diamonds look bigger than round diamonds of the same carat?

Oval diamonds have a larger surface area face-up than round diamonds of the same carat weight. Their elongated shape spreads the stone across more finger width and length, creating the appearance of a larger stone. A 1.00ct oval typically looks comparable to a 1.15–1.20ct round from above.

What length-to-width ratio is best for an oval diamond?

Most oval diamonds fall between 1.3 and 1.6 length-to-width ratio. A ratio of 1.3–1.4 produces a rounder, fuller oval; 1.5–1.6 produces a more elongated, slender appearance. The best ratio depends on personal preference and hand shape.

Oval Cut Diamonds: Why They're So Popular and What to Watch For

Why Oval Has Taken Over

The oval brilliant cut has become one of the most requested diamond shapes for engagement rings over the past decade, and for understandable reasons. It combines the brilliance of a round brilliant — both are cut with the same facet count and arrangement — with an elongated outline that makes the stone appear larger face-up than a round of the same carat weight. On most hand shapes, the oval's length also creates a flattering, finger-lengthening visual effect.

It is a shape that reads as distinctive without being unconventional. For buyers who want something other than a standard round but don't want an unusual shape, the oval sits in exactly the right position.

The Bowtie Effect

The most important quality consideration specific to oval cuts is the bowtie. A bowtie is a dark shadow that appears across the middle of many oval (and pear, marquise, and other elongated) diamonds when viewed face-up. It is caused by the geometry of the elongated shape: light entering the stone from certain angles exits without fully reflecting, creating a dark band in the centre of the stone.

All oval diamonds have some degree of bowtie. A faint bowtie is generally considered acceptable and can even add character. A severe bowtie — a wide, dark band visible from across a room — significantly diminishes the stone's face-up appearance and should be avoided.

The bowtie cannot be reliably assessed from a certificate. A GIA report grading a stone as Excellent cut does not account for bowtie severity; the standard grading criteria apply to round brilliants. For oval diamonds, the only reliable assessment is visual — viewing the stone in person or in video footage under consistent lighting. This is one strong argument for buying an oval diamond from a supplier or jeweller who can show you the stone directly.

Length-to-Width Ratio

The proportions of an oval — how elongated it appears relative to its width — are described by the length-to-width ratio (L/W ratio). A ratio of 1.0 would be a circle; most oval diamonds fall between 1.3 and 1.6.

A ratio of 1.3–1.4 produces a rounder, more compact oval that reads as softer and broader. A ratio of 1.5–1.6 produces a more elongated, slender shape that reads as more dramatic and creates a stronger finger-lengthening effect. Preferences vary — both ends of the range are commonly chosen — but it's worth knowing your preference before viewing stones, as the difference in appearance is significant.

Ratios above 1.6 exist and can look very striking, but become more susceptible to pronounced bowties at the extremes.

Colour Considerations

Oval diamonds show colour slightly more than round brilliants of the same grade. The elongated shape concentrates colour at the pointed tips of the stone, which can make lower colour grades more visible. As a practical guide: for a white-looking oval in a white gold or platinum setting, G or better is the safe choice. H can look very good in yellow gold settings, where the warm metal tone masks any hint of warmth in the stone. Going below H in white metal settings risks visible colour at the tips, particularly in larger stones.

Settings That Work Well with Oval Diamonds

The oval's elongated outline is shown to best advantage in settings that don't visually interrupt its length. A simple claw solitaire — four or six prongs — allows the stone to read fully. East-west (horizontal) settings, where the oval is rotated 90 degrees and set lengthways across the finger rather than pointing up the finger, have become a distinctive contemporary choice that reads as genuinely different from the standard orientation.

Halo settings work well with ovals but require careful proportioning — the surrounding diamonds should be small enough not to overwhelm the centre stone's outline. A thin halo with delicate stones enhances the oval; an oversized halo can make the combination look heavy and obscure the shape.

Pavé-set bands complement oval solitaires without competing with the centre stone. Plain metal bands in the same metal as the setting offer the cleanest presentation.

Book a consultation to view oval diamonds and discuss setting options, or message us on WhatsApp with any questions.