Round vs Emerald cut diamond size

By HeyGema™ · Updated November 5, 2026

In short

A 1 carat round measures 6.5 mm and a 1 carat emerald cut 7.0 x 5.0 mm. At the same weight an emerald cut faces up about 4% larger than a round. In face-up terms, 1 carat of round looks like a 1.00 carat round and 1 carat of emerald cut like a 1.06 carat round.

6.5 mm1 ct round
7.0 x 5.0 mm1 ct emerald cut
+4%emerald cut face-up vs round

Carat to mm calculator

ShapeGemCaratLength to width

About 7.0 x 5.0 mm

An estimate for a well-cut stone. A deep or shallow cut faces up smaller or bigger.

1 ct round

6.5 mm

1 ct emerald cut

7.0 x 5.0 mm

Side by side

1 ct emerald cut inside 1 ct round

A 1 carat round and a 1 carat emerald cut diamond, to the same scale.

Round vs Emerald cut diamond size at the same weight

At the same weight an emerald cut faces up about 4% larger than a round. A 1 carat round measures 6.5 mm and a 1 carat emerald cut 7.0 x 5.0 mm. A 1 carat round faces up like a 1.00 carat round, and a 1 carat emerald cut like a 1.06 carat round.

0.5 carat: Round length x width: 5.1 mm; Emerald cut length x width: 5.6 x 4.0 mm; Emerald cut face-up vs round: +4%

0.75 carat: Round length x width: 5.9 mm; Emerald cut length x width: 6.4 x 4.5 mm; Emerald cut face-up vs round: +4%

1 carat: Round length x width: 6.5 mm; Emerald cut length x width: 7.0 x 5.0 mm; Emerald cut face-up vs round: +4%

1.5 carat: Round length x width: 7.4 mm; Emerald cut length x width: 8.0 x 5.7 mm; Emerald cut face-up vs round: +4%

2 carat: Round length x width: 8.1 mm; Emerald cut length x width: 8.8 x 6.3 mm; Emerald cut face-up vs round: +4%

3 carat: Round length x width: 9.3 mm; Emerald cut length x width: 10.1 x 7.2 mm; Emerald cut face-up vs round: +4%

Carat	Round length x width	Emerald cut length x width	Emerald cut face-up vs round
0.5 carat	5.1 mm	5.6 x 4.0 mm	+4%
0.75 carat	5.9 mm	6.4 x 4.5 mm	+4%
1 carat	6.5 mm	7.0 x 5.0 mm	+4%
1.5 carat	7.4 mm	8.0 x 5.7 mm	+4%
2 carat	8.1 mm	8.8 x 6.3 mm	+4%
3 carat	9.3 mm	10.1 x 7.2 mm	+4%

Round vs Emerald cut on a finger

A 1 carat round covers 39% of the width of a size 6 finger and a 1 carat emerald cut covers 30%. Long cuts sit along the finger, so their width is what shows across it.

5.7 mm stone on a 16.5 mm finger: it covers 35% of the widthA 1.5 carat emerald cut on a size 6 finger.

4: Finger width: 14.9 mm; 1.5 ct round covers: 50%; 1.5 ct emerald cut covers: 38%

5: Finger width: 15.7 mm; 1.5 ct round covers: 47%; 1.5 ct emerald cut covers: 36%

6: Finger width: 16.5 mm; 1.5 ct round covers: 45%; 1.5 ct emerald cut covers: 35%

7: Finger width: 17.3 mm; 1.5 ct round covers: 43%; 1.5 ct emerald cut covers: 33%

8: Finger width: 18.1 mm; 1.5 ct round covers: 41%; 1.5 ct emerald cut covers: 32%

US ring size	Finger width	1.5 ct round covers	1.5 ct emerald cut covers
4	14.9 mm	50%	38%
5	15.7 mm	47%	36%
6	16.5 mm	45%	35%
7	17.3 mm	43%	33%
8	18.1 mm	41%	32%

Match the look, not only the carat

Because an emerald cut of about 0.95 carat faces up like 1 carat of round, comparing by weight alone hides the difference. Compare millimeters, or put both stones side by side in the size comparison tool.

Round and Emerald cut size charts

Full charts from 0.25 to 5 carat: Round diamond size chart and Emerald cut diamond size chart.

Questions

At the same weight an emerald cut faces up about 4% larger than a round. Face-up area is what you see from above; the emerald cut has more of it at equal weight.

A 1 carat round is about 6.5 mm and a 1 carat emerald cut about 7.0 x 5.0 mm, for a well-cut stone at the usual ratio.

A 2 carat round is 8.1 mm and a 2 carat emerald cut is 8.8 x 6.3 mm. Face-up, the emerald cut is +4% against the round.

A 1 carat round covers 39% of the width of a size 6 finger and a 1 carat emerald cut 30%. The numbers change with ring size and with the stone's length-to-width ratio.