A diamond’s shape is often the very first decision a buyer makes, and it has a huge effect on both the stone’s personality and its price. “Shape” refers to the outline of the diamond when viewed from above; it’s a separate consideration from “cut,” which refers to the quality of the proportioning and faceting within that shape.
Each shape has its own character, price profile, and things to watch for. Here’s a practical guide to the most popular options.
Round Brilliant
The round brilliant is the most popular diamond shape by a wide margin, accounting for the majority of diamonds sold. Its 57 or 58 facets are mathematically optimised to maximise brilliance and fire, making it the best-performing shape for pure sparkle.
The trade-off is cost: because more rough diamond material is lost cutting a round shape compared to other shapes, round brilliants typically cost 25-35% more than a fancy shape of equivalent carat weight, color, and clarity. If maximum sparkle is your priority and budget allows, round is the classic, safe choice.
Oval
Oval diamonds have surged in popularity in recent years. They offer nearly as much brilliance as a round brilliant while appearing larger for the same carat weight, thanks to their elongated shape. Ovals also tend to flatter the finger when set in a ring.
The main thing to watch for is the “bow-tie effect” — a dark, bow-tie-shaped shadow that can appear across the centre of the stone due to light leakage. Not all ovals show this, and a well-cut stone minimises it, but it’s worth viewing the actual diamond (or detailed video) before buying, since this is highly cut-dependent and not something a certificate alone will tell you.
Princess
Princess cuts are square or rectangular with pointed corners, offering a modern, geometric look with excellent brilliance — second only to round brilliants for sparkle. Because more of the rough diamond is retained during cutting compared to round shapes, princess cuts are generally more affordable per carat.
The pointed corners are more vulnerable to chipping than rounded shapes, so a setting with corner protection (like prongs covering each point) is worth discussing with your jeweller.
Cushion
Cushion cuts combine a square or rectangular shape with rounded corners and larger facets, giving a soft, romantic, vintage-inspired look. They tend to show off color more than other shapes (larger facets mean less light dispersion to mask warmth), so many buyers choose a slightly higher color grade — G or above — for cushion cuts specifically.
Emerald
Emerald cuts are rectangular with cropped corners and step-cut facets (long, parallel facets rather than the triangular facets of a brilliant cut). This creates a hall-of-mirrors effect rather than intense sparkle — elegant and understated rather than flashy.
Because the open facets make inclusions more visible (there’s no sparkle to distract the eye), clarity matters more for emerald cuts than for brilliant shapes. Aim for VS1 or better if choosing this shape, and always view the actual stone or high-resolution images before buying.
Pear and Marquise
Pear (teardrop) and marquise (elongated with pointed ends) shapes are distinctive, elongated cuts that also create a flattering, finger-lengthening effect and can appear larger than their carat weight suggests. Both carry a similar bow-tie risk to ovals and benefit from careful in-person or video viewing before purchase.
Symmetry matters enormously for both shapes — an off-centre point or uneven curves are far more noticeable than in a round or square stone, so check the certificate’s symmetry grade carefully.
How to Choose
There’s no objectively “best” shape — only the best shape for you. A few practical starting points:
Want maximum sparkle and a timeless, safe choice: round brilliant.
Want a stone that looks larger for your budget: oval, pear, or marquise.
Want strong sparkle at a lower price point than round: princess.
Want a vintage, romantic feel: cushion.
Want understated elegance over sparkle: emerald.
Whichever shape you choose, always ask to see the actual stone (in person or via high-resolution video) rather than relying on the certificate alone — shape-specific issues like bow-ties and symmetry are things a grading report doesn’t fully capture.