Diamond Education

Carat Weight

What is minimum individual carat weight?
Minimum individual carat weight is the minimum carat weight of one diamond in a piece of jewelry. If a pair of diamond stud earrings has a total diamond weight of 1/2 carat, the individual carat weight of each diamond would be 1/4 carat. The actual diamonds you purchase may weigh slightly more or less than the fractional weight specified. The Federal Trade Commission has strict guidelines about the disclosure of the range of carat weight that a fraction can represent. The chart below outlines acceptable ranges for carat weights expressed as fractions. Some diamonds may be cut into sizes between these more common fractions. Because it is more unusual for diamonds to be cut into these in-between sizes, ranges are not defined for these sizes. These sizes would have their specific carat weight (e.g., 0.62 carats) listed under minimum individual carat weight.

1/4 carat total weight may be 0.21 to 0.29 carats
1/3 carat total weight may be 0.30 to 0.36 carats
1/2 carat total weight may be 0.45 to 0.59 carats
3/4 carat total weight may be 0.70 to 0.84 carats
1 carat total weight may be 0.95 to 1.10 carats
1 1/4 carats total weight may be 1.20 to 1.29 carats
1 1/2 carats total weight may be 1.45 to 1.55 carats
2 carats total weight may be 1.95 to 2.05 carats

Cut

In order to best utilize a diamond gemstone's superlative material properties, a number of different diamond cuts have been developed. A diamond cut constitutes a more or less symmetrical arrangement of facets which together modify the shape and appearance of a diamond crystal. Diamond cutters must consider several factors, such as the shape and size of the crystal, when choosing a cut.

The most popular of diamond cuts is the modern round brilliant, whose facet arrangements and proportions have been perfected by both mathematical and empirical analysis. Also popular are the fancy cuts which come in a variety of shapes?many of which were derived from the round brilliant. A diamond's cut is evaluated by trained graders, with higher grades given to stones whose symmetry and proportions most closely match the particular "ideal" used as a benchmark. The strictest standards are applied to the round brilliant; although its facet count is invariable, its proportions are not.

The modern round brilliant (Figure 1 and 2) consists of 58 facets (or 57 if the culet is excluded); 33 on the crown (the top half above the middle or girdle of the stone) and 25 on the pavilion (the lower half below the girdle). The girdle may be frosted, polished smooth, or faceted. In recent decades, most girdles are faceted; many have 32, 64, 80, or 96 facets (People's Diamonds has a distinctive 100 facet cut; these facets are excluded from the total facet count. Likewise, some diamonds may have a number of small extra facets on the crown or pavilion that were created to remove surface imperfections during the diamond cutting process. Depending on their size and location, they may negatively impact the symmetry of the cut and are therefore considered during cut grading.

Color

A chemically pure and structurally perfect diamond is perfectly transparent with no hue, or color. However, in reality almost no gem-sized natural diamonds are absolutely perfect. The color of a diamond may be affected by chemical impurities and/or structural defects in the crystal lattice. Depending on the hue and intensity of a diamond's coloration, a diamond's color can either detract from or enhance its value. For example, most white diamonds are discounted in price when more yellow hue is detectable, while intense pink or blue diamonds (such as the Hope Diamond) can be dramatically more valuable. Out of all colored diamonds, red diamonds are the rarest of all.

The Gemological Institute of America (GIA) uses a "D" to "Z" scale it developed for grading the color of "white" (non-fancy colored) diamonds, where "D" is colorless and "Z" is yellow:

colorless: D, E, F
near colorless: G, H, I, J
faint yellow or brown: K, L, M
very light yellow or brown: N, O, P, Q, R
light yellow or brown: S, T, U, V, W, X, Y, Z

Diamonds occur in a restricted variety of colors ? steel gray, white, blue, yellow, orange, red, green, pink to purple, brown, and black. Colored diamonds contain interstitial impurities or structural defects that cause the coloration, whilst pure diamonds (which are exceedingly rare) are perfectly transparent and colorless.

Clarity

Diamond clarity is a quality of diamonds relating to the existence and visual appearance of internal defects of a diamond called inclusions, and surface defects called blemishes. Clarity is one of the four Cs of diamond grading, the others being carat, color, and cut. Inclusions may be crystals of a foreign material or another diamond crystal, or structural imperfections such as tiny cracks that can appear whitish or cloudy. The number, size, color, relative location, orientation, and visibility of inclusions can all affect the relative clarity of a diamond. A clarity grade is assigned based on the overall appearance of the stone under 10x magnification.

Most inclusions present in gem-quality diamonds do not affect the diamonds' performance or structural integrity. However, large clouds can affect a diamond's ability to transmit and scatter light. Large cracks close to or breaking the surface may reduce a diamond's resistance to fracture.

Diamonds with higher clarity grades are more valued, with the exceedingly rare "flawless" graded diamond fetching the highest price. However, minor inclusions or blemishes are sometimes considered to have some value, as they can be used as unique identifying marks analogous to fingerprints. In addition, as synthetic diamond technology improves and distinguishing between natural and synthetic diamonds becomes more difficult, inclusions or blemishes can be used as proof of natural origin.

FL-Flawless
These stones have no imperfections inside or on the outside of the stone under the magnification of a loupe of 10 power.

IF-Internally Flawless
These stones have no inclusions under a loupe with a 10 power magnification.

VVS1,VVS2-Very Very Slightly Imperfect
These stones have very small inclusions which are very difficult to see under a loupe with a 10 power magnification.

VS1,VS2-Very Slightly Imperfect
These stones have small inclusions which are slightly difficult to difficult to see under a loupe with a 10 power magnification.

SI1,SI2-Slightly Imperfect
These stones have inclusions which are fairly easy to see under a loupe with a 10 power magnification, or visible to the naked eye.

I1,I2,I3-Imperfect
These stones have inclusions which range from eye visible to very easily seen to the naked eye.