Does a 3 carat radiant look bigger than a round of the same weight?

Yes. It covers about 1% more face-up area than a 3 carat round, so it reads about the size of a 3.04 carat round.

What setting fits a 3 carat radiant diamond?

A 3 carat radiant sits in solitaire, three stone, cathedral and east–west. The seat to order is 8.09 mm for a solitaire, measured across the axis that crosses the finger.

IfTheRingFits

How big is a 3 carat radiant diamond?

Q: How big is a 3 carat radiant diamond?

A 3 carat radiant diamond measures about 9.22 by 7.69 millimetres and covers roughly 68.2 square millimetres seen from above.

A 3 carat radiant measures about 9.22 × 7.69 mm and covers roughly 68.2 mm² seen from above.

It reads about the size of a 3.04 ct round. Face-up it covers about 1% more area than a round of the same weight, because 3.00 ct spread into a longer outline shows more of itself from above.

The numbers

Length × width	9.22 × 7.69 mm
Length to width ratio	1.20 : 1
Depth	5.23 mm
Face-up area	68.2 mm²
Same weight, round	9.28 mm across, 67.6 mm²
Looks like a round of	3.04 ct

Calculated from standard weight factors and typical proportions. A particular stone's certificate is the exact answer; these are what to expect.

How wide is that on a finger?

A stone's width is what crosses the finger, and the same 7.69 mm reads differently depending on whose hand it is on — which is why photographs of other people's hands mislead.

Ring size (US)	Finger width	Stone covers
5	16.79 mm	46% of the width
6.5	18.10 mm	42% of the width
8	19.40 mm	40% of the width

Finger width is estimated from ring size at the average of three cross-sections, so treat it as a guide. The tool measures your own finger from a photograph instead.

Will it fit the setting?

A head is built around a seat of a particular diameter, and clearances run a tenth to half a millimetre — so a stone can be exactly the size you wanted and still not sit in the ring you picked. What each common style does with a 9.22 × 7.69 mm radiant:

Style	Seat to order	This stone in it
Solitaire	8.09 mm	Made for a stone this size
Halo	7.37 mm	Will not sit — too wide for the head
Three stone	8.09 mm	Made for a stone this size
Bezel	7.37 mm	Will not sit — too wide for the head
Cathedral	8.09 mm	Made for a stone this size
East–west	9.62 mm	Made for a stone this size

4 of 6 common styles take it. The seat is what the head should be ordered in, not a fixed figure: a head is made in a range and this is the point in that range this stone wants.

These are approximate reference values, not manufacturer specifications. Half a millimetre of error flips the answer, so use the seat diameter from the actual product page whenever you have one.

See it at true size

Photograph your hand, set the scale from a bank card or your ring size, and this 3 ct radiant is drawn at its real 9.22 × 7.69 mm on your own finger. The photo is processed on your device and never uploaded.

See a 3 ct radiant on your hand →

The same shape at other weights

0.25 carat radiant — 4.03 × 3.36 mm
0.5 carat radiant — 5.08 × 4.23 mm
0.75 carat radiant — 5.81 × 4.84 mm
1 carat radiant — 6.39 × 5.33 mm
1.25 carat radiant — 6.89 × 5.74 mm
1.5 carat radiant — 7.32 × 6.10 mm
2 carat radiant — 8.06 × 6.71 mm
2.5 carat radiant — 8.68 × 7.23 mm

The same weight in other shapes

3 carat oval — 11.41 × 8.15 mm
3 carat cushion — 8.42 × 8.02 mm
3 carat pear — 12.17 × 7.85 mm
3 carat marquise — 14.08 × 7.41 mm
3 carat emerald — 10.42 × 7.44 mm
3 carat princess — 7.91 × 7.91 mm
3 carat asscher — 8.20 × 8.20 mm

All shapes at 3 carat →