Carat is a measure of weight, not size. Two one-carat diamonds can look noticeably different on the hand depending on their shape and cut. If visible size matters to you, shape is your secret weapon.

What makes a diamond look big?

It's all about face-up surface area (spread). Shapes that are longer and shallower show more surface for the same weight.

Shapes ranked by face-up size

1. Marquise: the largest face-up area per carat of any shape, thanks to its long, narrow outline.
2. Oval: looks significantly larger than a round of the same weight, while keeping lots of sparkle.
3. Pear: elongated with a flattering teardrop outline.
4. Emerald: a long rectangular outline gives good spread, though step facets show less sparkle.
5. Radiant and cushion: can look slightly smaller, as more weight sits in the depth.
6. Round: the most brilliant, but not the largest-looking per carat.
7. Princess and Asscher: square shapes with deeper cuts that look more compact.

Cut proportions matter too

A diamond that's cut too deep hides weight underneath; one cut too shallow leaks light. Look for well-proportioned stones: an Excellent cut grade for rounds, and good length-to-width ratios for fancy shapes (for example around 1.35–1.50 for ovals).

Settings that add size

  • Halo: a ring of small diamonds makes the centre look bigger.
  • Thin bands: make the centre look larger by contrast.
  • White metal prongs blend into a colourless stone.

Lab-grown advantage

With lab-grown diamonds, you can often go up in carat as well as choosing a size-maximising shape. See our diamond shapes page or ask for options.