Diamond Cut Guides

 

The beauty of a diamond depends more on cut than any other factor. Diamond cut has three primary effects on appearance: brilliance (the brightness created by the combination of all the white light reflections from the surface and the inside of a polished diamond), fire (the dispersion of light into the colors of the visible spectrum, seen as flashes of color), and scintillation (the flashes of light and dark, or sparkle, when a diamond or light source is moved).

When a diamond is fashioned from a rough stone, the cutter must balance optimal cut (and therefore appearance) against maximum yield (cutting the diamond to maintain as much carat weight from the rough stone as possible). Because many customers are willing to pay more for a larger, fair-cut cut diamond than for a slightly smaller, well-cut diamond, there is pressure on the cutter to sacrifice appearance for weight. This is why the cut is so important.

For the larger and more expensive diamonds dealers will be willing to provide more detailed grading reports with diagrams ,as above,showing proportions of the diamond.Use the tables below to ensure you are getting the best value for money.

ROUND DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	53 – 58	52 – 53 or 58 – 60	51 or 61 – 64	50 or 65 – 69	< 50 or > 69
Depth %	59 – 62.3	58 – 58.9 or 62.4 – 63.5	57.5 – 57.9 or 63.6 – 64.1	56.5 – 57.4 or 64.2 – 65	< 56.5 or > 65
Crown Angle	34 – 34.9	32.1 – 33.9 or 35 – 35.9	30.1 – 32 or 36 – 37.9	29 – 30 or 38 – 40.5	< 29 or > 40.5
Pavilion Depth	42.8 – 43.2	42 – 42.7 or 43.3 – 43.9	41 – 41.9 or 44 – 45.5	39 – 40.9 or 45.6 – 48	< 39 or > 48
Girdle	Thin to Sl. Thick	Very Thin to Sl. Thick	Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	1.00 – 1.01			1.02	> 1.02

PRINCESS CUT DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	62 – 70	59 – 61 or 71 – 74	56 – 58 or 75 – 82	53 – 55 or 83 – 85	< 53 or > 85
Depth %	64 – 75		58 – 63.9 or 75.1 – 80	56 – 57.9 or 80.1 – 84	< 56 or > 84
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	1.00 – 1.03		1.04 – 1.05	1.06 – 1.08	> 1.08

OVAL DIAMONDS – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	53 – 63	52 or 64 – 65	51 or 66 – 68	50 or 69 – 70	< 50 or > 70
Depth %	58 – 62	56 – 57.9 or 62.1 – 66	53 – 55.9 or 66.1 – 71	50 – 52.9 or 71.1 – 74	< 50 or > 74
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	1.35 – 1.50	1.30 – 1.34 or 1.51 – 1.55	1.25 – 1.29 or 1.56 – 1.60	1.20 – 1.24 or 1.61 – 1.65	> 1.20 or < 1.65

MARQUISE DIAMONDS – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	53 – 63	52 or 64 – 65	51 or 66 – 68	50 or 69 – 70	< 50 or > 70
Depth %	58 – 62	56 – 57.9 or 62.1 – 66	53 – 55.9 or 66.1 – 71	50 – 52.9 or 71.1 – 74	< 50 or > 74
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	1.85 – 2.00	1.75 – 1.84 or 2.01 – 2.15	1.65 – 1.74 or 2.16 – 2.30	1.55 – 1.64 or 2.31 – 2.45	> 1.55 or < 2.45

PEAR SHAPED DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	53 – 63	52 or 64 – 65	51 or 66 – 68	50 or 69 – 70	< 50 or > 70
Depth %	58 – 62	56 – 57.9 or 62.1 – 66	53 – 55.9 or 66.1 – 71	50 – 52.9 or 71.1 – 74	< 50 or > 74
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	1.45 – 1.55	1.40 – 1.44 or 1.56 – 1.65	1.35 – 1.39 or 1.66 – 1.80	1.25 – 1.34 or 1.81 – 2.00	> 1.25 or < 2.00

CUSHION CUT DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	61 – 67	58 – 60 or 68 – 70	56 – 57 or 71	54 – 55 or 72 – 73	< 54 or > 73
Depth %	61 – 67	58 – 60.9 or 67.1 – 70	56 – 57.9 or 70.1 – 71	54 – 55.9 or 71.1 – 73	< 54 or > 73
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium

EMERALD CUT DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	61 – 69	57 – 60 or 70 – 72	54 – 56 or 73 – 74	51 – 53 or 75 – 79	< 51 or > 79
Depth %	61 – 67	59 – 60.9 or 67.1 – 70	57 – 58.9 or 70.1 – 74	54 – 56.9 or 74.1 – 79	< 54 or > 79
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium

ASSCHER CUT DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	61 – 69	57 – 60 or 70 – 72	54 – 56 or 73 – 74	51 – 53 or 75 – 79	< 51 or > 79
Depth %	61 – 67	59 – 60.9 or 67.1 – 70	57 – 58.9 or 70.1 – 74	54 – 56.9 or 74.1 – 79	< 54 or > 79
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	1.00 – 1.03		1.04 – 1.05	1.06 – 1.08	> 1.08

RADIANT CUT DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	61 – 69	57 – 60 or 70 – 72	54 – 56 or 73 – 74	51 – 53 or 75 – 79	< 51 or > 79
Depth %	61 – 67	59 – 60.9 or 67.1 – 70	57 – 58.9 or 70.1 – 74	54 – 56.9 or 74.1 – 79	< 54 or > 79
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium

HEART SHAPED DIAMOND – CUT GUIDE

	EXCELLENT	VERY GOOD	GOOD	FAIR	POOR
Table %	53 – 63	52 or 64 – 65	51 or 66 – 68	50 or 69 – 70	< 50 or > 70
Depth %	58 – 62	56 – 57.9 or 62.1 – 66	53 – 55.9 or 66.1 – 71	50 – 52.9 or 71.1 – 74	< 50 or > 74
Girdle	Very Thin – Slightly Thick		Very Thin to Thick	Very Thin to Very Thick	Ex. Thin to Ex. Thick
Culet	None	Very Small	Small	Medium	> Medium
L/W Ratio	.95 – 1.02	.89 – .94 or 1.03 – 1.05	.83 – .87 or 1.06 – 1.10	.80 – .83 or 1.11 – 1.15	> .80 or < 1.15