Diamond Sizes in MM

Welcome to Diamond Size Charts, an online comprehensive tool to aid you in finding out diamonds sizes in mm and vice versa in a matter of seconds. It was developed with the generous help of Ava Diamonds and their esteemed gemologists to ensure reliability and maximum accuracy. Besides pre-calculated ct/mm conversions you will also find other useful information such as ideal length to width ratios, as well as depth and table recommendations to provide tools for maximizing your diamond selection.

Professional Brilliant Round Cut Diamond Carat MM Conversion

MM to CT Round Cut Size Comparison Tool

Ever wondered what a 7mm brilliant round cut diamond is in carats, or how many mm is a 2 carat diamond? The following chart will help you do all of that and much more, including sizes from melee to large carat diamonds.

The Brilliant Round Cut Diamond is the most popular diamond shape today by a large margin. As a result, the tiniest of inaccuracies that weren’t discovered before purchasing or selling can translate to a significant reduction in profit. This is often lost in small mistakes between carats and mm and inaccurate conversions. Below you will find detailed diamond size charts that show the immediate conversions of ct to mm.

Brilliant Round Cut Diamond Carat MM / MM to CT Conversion Tool

0.21 – 5.20 cts

ROUND CUT CARAT WEIGHT	ROUND CUT MM SIZE
0.21 - 0.22 ct	3.80 - 3.90mm
0.23 - 0.24 ct	3.90 - 4.00mm
0.25 - 0.26 ct	4.00 - 4.10mm
0.26 - 0.27 ct	4.10 - 4.20mm
0.27- 0.28 ct	4.20 - 0.43 mm
0.30 -0.36 ct	4.40 - 4.50 mm
0.40 - 0.45 ct	4.60 - 4.70 mm
0.46 - 0.48 ct	4.90 - 5.00 mm
0.50 - 0.57 ct	5.10 - 5.30 mm
0.60 - 0.67 ct	5.40 - 5.60 mm
0.70 - 0.77 ct	5.70 - 5.90 mm
0.80 - 0.85 ct	6.00 - 6.10 mm
0.90 - 0.95 ct	6.20 - 6.30 mm
1.00 - 1.10 ct	6.40 - 6.60 mm
1.22 - 1.26 ct	6.70 - 6.80 mm
1.28 - 1.30 ct	6.90 - 7.10 mm
1.50 - 1.55 ct	7.20 - 7.40 mm
1.67 - 1.80 ct	7.50 - 7.90 mm
2.00 - 2.10 ct	8.10 - 8.30 mm
2.40 - 2.60 ct	8.50 - 8.80 mm
2.70 - 2.80 ct	8.90 - 9.10 mm
3.00 - 3.10 ct	9.20 - 9.40 mm
3.30 - 3.40 ct	9.50 - 9.60 mm
3.50 - 3.70 ct	6.70 - 7.80 mm
3.80 - 3.90 ct	9.90 - 10.00 mm
4.00 - 4.10 ct	10.10 - 10.20 mm
3.30 - 4.40 ct	10.30 - 10.50 mm
4.50 - 4.60 ct	10.60 - 10.70 mm
4.70 - 4.80 ct	10.80 - 10.90 mm
4.90 - 4.99 ct	10.90 - 11.00 mm
5.00 - 5.20 ct	11.10 - 11.20 mm

Ava Diamonds

Round Cut Melee Diamond Conversion of CT MM / MM to Carat And Sieve Size Chart

0.005 – 0.20 cts

Melee diamonds, categorized as diamonds between 0.005 and 0.15 carat stones are one of the greatest cost effective means of enhancing a jewelry piece. They are most common in pieces like Halo Rings, as well as custom jewelry designs. Round Melee diamonds in particular have additional characteristics to take extra notice of, which is why we’ve included a Round Diamond Sieve Chart to complement the ct to mm conversion.

ROUND CUT CARAT WEIGHT	ROUND CUT MM SIZE	CTS/PCS	ROUND CUT SIEVE SIZES
0.005 ct	0.90-1.10 mm	1/200	+000/-0
0.006 ct	1.10-1.15 mm	1/175	+0/-1
0.007 ct	1.15-1.20 mm	1/150	+1/-1.5
0.008 ct	1.20-1.25 mm	1/120	+1.5/-2
0.009 ct	1.25-1.30 mm	1/100	+2/-2.5
0.01 ct	130-1.35 mm	1/100	+2.5/-3
0.011 ct	1.35-1.40 mm	1/100	+3/-3.5
0.012 ct	1.40-1.45 mm	1/80	+3.5/-4
0.013 ct	1.45-1.50 mm	1/80	+4/-4.5
0.014 ct	1.50-1.55 mm	1/70	+4.5/-5
0.016 ct	1.55-1.60 mm	1/60	+5/-5.5
0.018 ct	1.60-1.70 mm	1/50	+5.5/-6
0.021 ct	1.70-1.80 mm	1/50	+6/-6.5
0.025 ct	1.80-1.90 mm	1/40	+6.5/-7
0.029 ct	1.90-2.00 mm	1/30	+7/-7.5
0.035 ct	2.00-2.10 mm	1/30	+7.5/-8
0.039 ct	2.10-2.20 mm	1/25	+8/-8.5
0.044 ct	2.20-2.30 mm	1/25	+8.5/-9
0.052 ct	2.30-2.40 mm	1/20	+9/-9.5
0.058 ct	2.40-2.50 mm	1/20	+9.5/-10
0.069 ct	2.50-2.60 mm	1/15	+10/-10.5
0.074 ct	2.60-2.70 mm	1/15	+10.5/-11
0.078 ct	2.70-2.80 mm	1/12	+11/-11.5
0.086 ct	2.80-2.90 mm	1/12	+11.5/-12
0.095 ct	2.90-3.00 mm	1/10	+12/-12.5
0.108 ct	3.00-3.10 mm	1/10	+12.5/-13
0.116 ct	3.10-3.20 mm	1/8	+13/-13.5
0.13 ct	3.20-3.30 mm	1/8	+13.5/-14
0.145 ct	3.30-3.40 mm	1/6	+14/-14.5
0.155 ct	3.40-3.50 mm	1/6	+14.5/-15
0.165 ct	3.50-3.60 mm	1/6	+15/-15.5
0.19 ct	3.60-3.70 mm	1/5	+15.5/-15.75
0.20 ct	3.70-3.80 mm	1/5	+15.75/-16.5

Ava Diamonds

What are the Ideal Proportions of a Brilliant Round Cut?

The ideal proportions for the brilliant round cut diamond include several key factors which play a significant role in achieving the great light reflection and sparkle the cut rose to fame with. For example, the Pavilion Depth and Crown Angle, even at their most subtle of differences can mean a completely different end result and overall value.

Below you will find a shortcut listing the general estimations as calculated by the experienced staff of Ava Diamonds to help you see where you stand, and serve as a quick reminder when gauging your brilliant round cut diamond’s depth and table.

What is the Ideal Table and Depth for the Brilliant Round Cut Diamond?

	EXCELLENT	VERY GOOD	GOOD
Table - %	53% - 58%	52% - 53% or 58% - 60%	51% or 61% - 64%
Depth - %	59% - 62.3%	58% - 58.9% or 62.4% - 63.5%	57.5% - 57.9% or 63.6% - 64.1%
Crown Angle	34 - 34.9	32.1 - 33.9 or 35 - 35.9	30.1 - 32 or 36 - 37.9
Pavilion Depth - %	42.8% - 43.2%	42% - 42.7% or 43.3% - 43.9%	41% - 41.9% or 44%- 45.5%
Girdle	Thin to Sl. Thick	Very Thin to Sl. Thick	Very Thin to Thick
Culet	None	Very Small	Small

What is the Ideal Brilliant Round Cut Diamond Length to Width Ratio?

The length to width ratio is an extremely valuable piece of information that can provide an estimation of how a round cut diamond will appear when viewed from above. A significant factor in jewelry design, and as a result, it has great significance for traders as well.

	EXCELLENT / VERY GOOD	GOOD
Length To Width Ratio	0.99 - 1.01	0.98-1.01