Carat Weight
Also called ct, diamond carat, carat
Carat weight is the unit used to measure how heavy a diamond or gemstone is. One carat equals 0.2 grams and divides into 100 points, so a 0.50 carat stone is a fifty pointer. Carat measures mass, not width across the top.
In other words, it tells you what the stone weighs on the scale. Two stones of the same carat weight can still look different sizes face up.
Weight is not the same as spread
Buyers think in millimetres across the top, but the trade sells by weight. A deeply cut stone hides some of its weight in the pavilion, so it looks smaller face up than a shallower stone of the same carat.
Denser materials weigh more for the same size. A cubic zirconia of the same millimetre size as a diamond weighs noticeably more, which is why CZ is usually quoted in diamond equivalent millimetres rather than carats.
Why it matters for rendering
We build the stone in the render at the millimetre size that matches the carat weight you quote. Get this wrong and the whole piece reads at the wrong scale: a 6.5mm round in a head modelled for 5mm will crowd the prongs and sit too high.
Carat weight also changes how the metal around it reads. A 2 carat centre needs a heavier head and thicker shoulders, and if the render shows a delicate setting under a large stone the factory piece will not match the picture.
What to send us
If your CAD already contains the stone at the correct size, we work from that and nothing else is needed. If the file has a placeholder stone, tell us the carat weight or the millimetre size and we will swap it before rendering.
For rings sold in a range of centre sizes, pick the one that leads on the listing. Extra sizes can go through as separate files.
Questions about Carat Weight
How many millimetres is a 1 carat diamond?
A well proportioned 1 carat round brilliant is around 6.4 to 6.5mm across. Fancy shapes vary, because length, width, and depth all trade off against each other.
Is carat the same as karat?
No. Carat is stone weight. Karat is gold purity, as in 14K or 18K. They are separate measures that happen to sound alike.
Can you render a ring in several carat sizes?
Yes. Each size is a separate CAD file at $15, and each comes back as 9 HD images and 3 videos in rose, white, and yellow gold.