Diamond’s Cut

Most gemologists will agree that, of all the four C’s, cut is the most important. The cut of a diamond influences the way it reflects light, which in turn determines its brilliance. Even a diamond with perfect color and clarity may appear lifeless if it does not have a good cut.

In a well-cut diamond, light enters the stone and is reflected around the mirror-like facets before exiting through the top, or table. This careful orchestration of the movement of light inside the stone and back to the eye is what causes the fiery sparkle we recognize as brilliance. A skilled professional can maximize this effect by cutting a diamond to very precise proportions. Too shallow a cut will allow light to escape through the bottom of the stone, causing it to look dull. Too deep a cut will cause light to be lost through the diamond’s sides, making it appear dark.

Illustration of Diamond Cut

Depth is not the only important factor; other angles and proportions matter as well. In fact diamond cutters now use sophisticated computer modeling tools to give them a full picture of how light will behave inside a stone, allowing them to adjust proportions to optimize a diamond’s brilliance, as well as its brightness, scintillation, and fire, the qualities known collectively as the diamond’s “face-up appearance.”

14K White Gold Round Diamond 4-Prong Stud Earrings (3/8ctw, J-K, I2-I3)	14k Gold, Round, Diamond Stud Earrings (1/4 cttw, I-J Color, I1-I2 Clarity)
2.14 cts Heart Shape Created Ruby and Genuine Diamonds Earring Studs – 14kt White or Yellow Gold	14k Two-Tone Diamond Hoops (1/8 cttw, H-I Color, I2 Clarity)

Some round diamonds come with certifications that supply their cut grade. The GIA (Gemological Institute of America) ranks diamonds as Excellent, Very Good, Good, or Fair. The AGS (American Gem Society) ranks them as Ideal, Excellent, Very Good, Good, or Fair. Amazon represents both Round GIA “Excellent cut” diamonds and Round AGS “Ideal cut” diamonds as “Ideal” on our site, since these two terms both refer to the highest quality of diamond cut.

10k White Gold Black Diamond Infinity Earrings (1/4 cttw)	14k Choice of White or Yellow Gold Black Diamond Studs (2 cttw)
14K White Gold Princess Diamond 4-Prong Stud Earrings (1/3ctw, J-K, I2-I3)	14k Yellow Gold 3/4″ (19mm) tall Lever Back Dangle Earrings, w/ 0.13 Carat Brilliant Cut Diamonds & 2.40 Carats Oval Cut 7×5mm Emerald Stones

Round cut diamonds, it should be noted, are the only ones that can achieve a grading of “Ideal.” Other cuts, such as Princess, Asscher, or Emerald, will receive, at the highest, a grading of “Very Good.” For diamonds that do not have AGS or GIA certifications, Amazon will calculate the cut based on the stone’s depth, table percentages, symmetry and polish.

Ideal
A diamond described as Ideal represents the highest standards of cut, with only the top 3% of all diamonds falling in this category. An Ideal Cut diamond reflects nearly all the light that enters it and displays maximum brilliance and fire. For those who want the very best that money can buy, this is the cut to choose.

Very Good
A diamond described as Very Good reflects nearly as much light as an Ideal cut diamond, and represents approximately the top 15% of diamonds based on cut. The proportions may overlap with many of the proportions of an Ideal cut, with slight variations from the preferred range that allow the cutter to create a larger stone. A diamond with a Very Good cut has exceptional brilliance and is generally priced slightly lower than an Ideal cut diamond.

Good
A diamond described as Good reflects most of the light that enters it, and is much less expensive than a Very Good cut. A diamond in this category represents roughly the top 25% of diamonds based on cut. Its proportions may vary from the preferred range because the cutter has opted to maximize the size of the stone rather than creating a smaller Very Good quality diamond. For those shopping on a budget, a diamond in this range offers good quality and excellent value.

Fair
A diamond described as Fair represents the top 35% of diamonds based on cut. Though it is still a quality cut, it reflects less light and displays less brilliance than a Good Cut diamond. Diamonds in this range are typically cut to maximize size over other factors.

2.02 cts Genuine Blue Topaz and Diamond Heart Pendant – 14kt White or Yellow Gold	10k White Gold Diamond 3-Stone Heart Pendant (1/10 cttw, I-J Color, I2-I3 Clarity), 18″
10k White Gold Heart Diamond Pendant Necklace (HI, I, 0.10 carat)	2.02 cts Created Ruby and Genuine Diamond Heart Pendant – 14kt White or Yellow Gold

Diamond’s Clarity

No two diamonds are alike. A diamond’s most distinguishing characteristics are its inclusions, marks that are often invisible to the naked eye. However, under a jeweler’s magnifying loupe or microscope they can look like crystals, tiny rivers, or clouds. A diamond’s clarity is determined by the presence or absence of inclusions–fewer inclusions mean better clarity–and how visible they are. The greater a diamond’s clarity, the greater its brilliance and value. A diamond categorized as internally flawless will have no inclusions, but this is extremely rare.

Diamonds with very, very small inclusions are graded as VVS1 or VVS2. Those with larger inclusions are considered lower-grade. Diamonds with inclusions that are visible with the naked eye are graded I1 to I2.

F / FLAWLESS
The diamond shows no inclusions or blemishes of any sort under 10X magnification when observed by an experienced grader. Note: Truly flawless or internally flawless (F or IF on the GIA’s grading scale) diamonds are extremely rare.

IF / INTERNALLY FLAWLESS
The diamond has no inclusions when examined by an experienced grader using 10X magnification, but will have some minor blemishes.

VVS1, VVS2 / VERY, VERY SLIGHTLY INCLUDED
The diamond contains minute inclusions that are difficult even for experienced graders to see under 10X magnification.

VS1, VS2 / VERY SLIGHTLY INCLUDED
The diamond contains minute inclusions such as small crystals, clouds or feathers when observed with effort under 10X magnification.

SI1, SI2 / SLIGHTLY INCLUDED
The diamond contains inclusions (clouds, included crystals, knots, cavities, and feathers) that are noticeable to an experienced grader under 10X magnification.

I1, I2, I3 / INCLUDED
The diamond contains inclusions (possibly large feathers or large included crystals) that are obvious under 10X magnification and may affect transparency and brilliance.

14k White or Yellow Gold Shared Prong Diamond Eternity Band (3 cttw, H-I Color, SI2 Clarity)	14k White or Yellow Gold Channel Set Diamond Eternity Band (1 cttw, H-I Color, SI2 Clarity)
14k White or Yellow Gold Shared Prong Diamond Eternity Band (2 cttw, H-I Color, SI2 Clarity)	1/2ctw Diamond Prong Set Eternity Band in 14k White Gold

Diamond’s Color

Though diamonds come in a wide range of colors, colorless diamonds have traditionally been considered the most valuable. Most diamonds are graded on a scale using the letters of the alphabet, from D (colorless), the best grade, through Z (a light yellow). It is difficult for the untrained eye to notice such variations in color unless stones are being compared side by side. The comparatively rare colored diamonds are known as fancy-colored and are also quite valuable. They range in hue from the more common yellow (also graded Z+ on the alphabetic scale) to pink, blue, green, red, and even black and white.

Illustration of Diamond Color

Diamonds that are graded D, E, and F tend to be the most expensive because of their rarity. However, any diamond you buy should have a good balance of cut, color, and clarity, so as to impart the most brilliance and dazzle possible.

14k Choice of White or Yellow Gold Diamond Promise Ring (1/10 cttw, H-I Color, I1-I2 Clarity)	10k White Gold Ring 3/8″ (10mm) wide, w/ 1.18 Total Carat Weight of Round Brilliant Diamonds Lab Created Pink Sapphire Stones
10k Choice of White or Yellow Gold Round Diamond Band (1/6 cttw, J-K Color, I2-I3 Clarity)	14k Two-Tone Diamond Heart Ring (1/10 cttw, H-I Color, I2 Clarity)

Diamond’s Carat

A diamond’s weight is measured in carats, with one carat being equivalent to 100 points. You will often see a diamond referred to as a 3/4-carat stone or a 75-point diamond. Larger stones are often more highly valued, but size should not be the only consideration–high brilliance, which varies according to clarity, cut, and color grade, is highly desirable in a diamond.

Carat Weight Scale

1.29 cts Genuine Round White Topaz and Diamond Engagement Ring – 14kt White or Yellow Gold	14K White Gold 3 Three Stone Round Diamond Ring (1/2 ctw)
10k White or Yellow Gold Round 7-Stone Ring (1/4 cttw, H-I Color, I2-I3 Clarity)	10k White Gold Blue and White Diamond 3-Stone Ring (.12 ct center, 1/4 cttw)