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Carat is weight, not size
Two one carat stones can look very different, because carat measures what a stone weighs and your eye measures what it covers.
Drawn to scale on screen at a nominal 96 pixels per inch. Your display may be a little off, so treat it as a close guide rather than a ruler.
Carat questions
- How big is a 1 carat diamond in millimetres?
- A one carat round brilliant is about 6.5mm across. Carat is a measure of weight rather than size, so the same weight in a different cut looks quite different: a one carat oval reads noticeably larger than a one carat round because more of its weight sits at the surface.
- Does a bigger carat always look bigger?
- No. An elongated cut such as oval, marquise or pear spreads its weight across a wider face, so it looks larger than a round of the same weight. A deep-cut stone hides weight in its depth and can look smaller than a shallower stone weighing less.
- What carat size looks best on a small hand?
- Anything from half a carat upward reads clearly on a slender finger, and an elongated cut flatters it further by lengthening the line of the hand. Size is relative to the finger, which is why a stone that looks modest in a photograph can look substantial in person.
- Is there a big price jump at 1 carat?
- Yes, and it is worth knowing. Prices step sharply at the round numbers because of demand rather than rarity, so a 0.9 carat stone is often materially cheaper than a 1.0 and around 3% smaller in diameter, which nobody can see.
- How do I know the millimetre size of my own stone?
- Measure across the widest point of the stone with a gauge or a ruler, or read it off the certificate, which states the dimensions. That measurement is more useful than the carat weight when you are picturing how it will look.