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Diamond Knowledge
DIAMOND KNOWLEDGE
The 4Cs: Carat, Clarity, Color, Cut
Every diamond, like every snowflake, is unique. Diamonds differ from one another in any one of four categories, referred to as the 4Cs:
- Carat Weight
- Clarity
- Color
- Cut
Using the 4Cs as criteria, gemologists grade each diamond to determine its value.
Magic Weights
The diamond market has defined several different "magic weights" for diamonds, which impact the price. A "magic weight" is the weight at which the value (or cost) per carat of the diamond increases. For example, a diamond that weighs 0.98 ct. can have a significantly lower cost than one that weighs 1.00 ct—with all other factors equal—because 1.00 ct is a "magic weight." The magic weights are .5 ct, .75 ct, 1 ct, 1.5 ct, and 2 ct. As the weight of a diamond increases, so does the price per carat. When shopping for a loose diamond, ask for the specific weight to verify that the price is relative to the exact carat weight.
Approximate Weight Size
This scale shows the typical size difference between round diamonds of increasing carat weight. This is just a general guide—every diamond is unique and proportions vary from diamond to diamond.
Carat Weight Ranges
Carat weights are often grouped together into fractions for ease of use. You'll see these fractions in the titles of our products, product details, and in our stores.
| Carat Weight | Weight Range |
| 1/20 | .04 – .06 |
| 1/15 | .07 – .07 |
| 1/12 | .08 – .08 |
| 1/10 | .09 – .11 |
| 1/8 | .12 – .13 |
| 1/7 | .14 – .15 |
| 1/6 | .16 – .17 |
| 1/5 | .18 – .22 |
| 1/4 | .23 – .29 |
| 1/3 | .30 – .37 |
| 3/8 | .38 – .46 |
| 1/2 | .47 – .59 |
| 5/8 | .60 – .69 |
| 3/4 | .70 – .79 |
| 7/8 | .80 – .89 |
| 9/10 | .90 – .95 |
| 1 | .96 – 1.05 |
| 1 1/4 | 1.23 – 1.29 |
| 1 1/2 | 1.47 – 1.59 |
| 1 3/4 | 1.70 – 1.79 |
| 2 | 1.96 – 2.10 |
| 2 1/2 | 2.47 – 2.59 |
| 3 | 2.96 – 3.10 |
Clarity Grades
There are 11 clarity grades that gemologists can assign to a diamond. Grading is done under 10x magnification and each clarity characteristic's size, position, and type is indicated on a diamond plot.
Flawless (FL)
No blemishes or inclusions under 10x magnification.
The following do not disqualify a stone from the flawless category:
- An extra facet on the pavilion which cannot be seen face up.
- Naturals totally confided to the girdle, which neither thickened the girdle nor distort its outline.
- Internal graining which is not reflective, white, or colored, and does not significantly affect transparency.
Internally Flawless (IF)
No inclusions and only significant blemishes under 10x magnification. Normally what separates IF from FL stones are characteristics that can be removed by minor repolishing (light surface graining is an exception).
Very, Very Slightly Included (VVS1 & VVS2)
Contain minute inclusions that are difficult for even the skilled grader to locate under 10x magnification. In VVS1, they are extremely difficult to see, visible only from the pavilion, or small and shallow enough to be removed by minor repolishing. In VVS2, the minor inclusions are very difficult to see.
Very Slightly Included (VS1 & VS2)
Contain minor inclusions ranging from difficult (VS1) to somewhat easy (VS2) for a trained grader to see under 10x magnification. Small included crystals, small feathers, and distinct clouds are typical.
Slightly Included (SI1 & SI2)
Contain noticeable inclusions which are easy (SI1) to very easy (SI2) to see under 10x magnification. In some SIs, inclusions can be seen with the unaided eye.
Included (I1, I2, & I3)
Contain inclusions which are obvious to a trained grader under 10x magnification, can often be easily seen face-up with the unaided eye, seriously affect the stone's potential durability, or are so numerous they affect transparency and brilliance.
I1 (Included: Level 1)
Moderate effect on beauty or durability. This is the first grade at which an inclusion can be seen with the naked eye, or without the 10x magnification. This is also the most common diamond grade found in the retail market today.
I2 (Included: Level 2)
Inclusions easily visible to the naked eye with a severe effect on beauty or durability. An I2 diamond is noticeably different from an I1 diamond. The I2 grade is given to a diamond that has several or very easily seen inclusions in it.
I3 (Included: Level 3)
Several very visible inclusions with a severe effect on beauty and durability. The lowest grade a diamond can receive and still be considered gem quality is I3, after which it becomes an industrial grade diamond. An I3 would have extremely visible inclusions. Often an I3 diamond has inclusions that can seriously threaten the durability of a diamond.
Color Grades
The diamond color chart is considered industry standard, with D (colorless) representing the best color grade available. The difference between each step can be very difficult to determine, especially to an untrained eye.
The most popular color range is Near Colorless (G-H) because diamonds in this range are more affordable, and when mounted can appear just as colorless as diamonds in the Colorless range. Typically, less color equals greater rarity, increasing the value of the diamond. But the natural presence of a fancy color can result in a cost that is more than a colorless, all things being equal. An example of a fancy color diamond is the famous Hope Diamond, which is a beautiful dark blue diamond.
Colorless
D E F
Near Colorless
G H I J
Faint Yellow
K L M
Very Light Yellow
N O P Q R
Light Yellow
S T U V W X Y Z
Fancy Yellow
Standard & Fancy Shapes
The standard round brilliant was the top-selling diamond cut for all of the 20th century. This immense popularity is no accident as it can maximize a diamond’s brilliance, dispersion, and scintillation. The design evolved over hundreds of years, along with cutting technology, scientific understanding of light, and modern appreciation of diamonds' beauty.
Any shape other than round brilliant is considered a fancy shape. Classic fancy shapes include emerald cut, oval, pear, heart, princess, and marquise. Lesser known or branded cuts are also available (cushion, trillion, and our own Noventa® Diamond)
Facet Arrangement
Facet arrangement is a little less commonly known. Most diamonds have one of three basic facet arrangements: brilliant, step, or mixed.
Brilliant cut diamonds have a facet pattern that radiates from the center of the stone toward the edge with triangle or kite shaped facets.
Step cut diamonds have concentric rows of trapezoidal facets running parallel to the girdle.
Mixed cut diamonds combine both brilliant cut facets and step cut facets; often this style is seen as a diamond with a step cut crown and a brilliant cut pavilion. Mixed cuts are not common.
Cut Quality
Whatever the shape, a well-cut diamond is the work of a master diamond cutter. When cut to good proportions, a diamond is better able to handle light, creating more scintillation (sparkle). Although many cannot see an actual difference in cut, they can appreciate and recognize the beauty of a well-cut diamond.
When a diamond is cut to good proportions, light is reflected from one facet to another and then dispersed through the top of the stone. If the cut of the diamond is too deep, some light escapes through the opposite side of the pavilion. If the cut is too shallow, light escapes out the pavilion walls before it can be reflected.
