Diamond Education
- CUT
- COLOR
- CLARITY
- CARAT
Cut is considered to be the most important of all of the diamond characteristics, as a well-cut diamond will often appear larger than a poorly cut diamond of the same carat weight, and have the appearance of enhanced color and clarity.
The quality of cut is determined by how well the symmetry, polish, and proportions of the diamond produce the most attractive balance of the three different types of reflection. Several proportion factors have the most immediate impact on a diamond's ability to reflect light correctly. The table size and depth of a diamond relative to the diameter greatly impacts the light return from a diamond. A well-cut diamond is proportioned so that most of the light entering the gem exits back through the top of the stone, perfectly balancing the white light (brilliance) with intense flashes of fire (dispersion). A poorly-cut diamond, with facets cut only a few degrees out of alignment, can result in light exiting through the bottom of the diamond, known as light leakage, instead of from the top where it is visible. This creates a diamond with dulled brilliance from poor light performance within the gem, making the center of the gem look dark. 
The best cut diamonds have proportions that are within tried and true ranges known for maximizing brilliance, fire, and scintillation. The cut grading scale for diamonds is based on the reflective properties of the diamond, according to these carefully calculated diamond measurements. It also allows you to easily identify a well-cut diamond, without having to assess each individual cut characteristic.
- Ideal: Exquisite quality cut to create the optimal combination of brilliance and fire. Reflects nearly all light that enters the diamond. Top 3% of diamond quality based on cut.
- Very Good: Superior quality cut that reflects nearly as much light as the ideal cut while at a substantially lower cost. Top 15% of diamond quality.
- Good: Premium quality cut to optimize the size without sacrificing quality or beauty. Reflects most light that enters. Top 25% of diamond quality.
- Fair: Adequate quality cut which reflects some light while maximizing weight. While not as brilliant as a good cut, still a quality diamond. Top 35% of diamond quality.
- Poor: Inadequate quality cut that reflects minimal amount of light.
DIAMOND CHARACTERISTICS
- Diameter: Width of diamond as measured through the girdle.
- Culet: The tiny facet at the bottom tip of a gemstone's pavilion. The optimal culet should be pointed or very small (graded "small" or "none").
- Table: The largest facet of a gemstone, located at the top. Determined as a percentage of the overall diameter of the gem.
- Crown: The top portion of the diamond, from the girdle to the table.
- Pavilion: The lower portion of a diamond, from the girdle to the culet.
- Girdle: The narrow rim around the widest part of a diamond, separating the crown from the pavillion. Also referred to as the setting edge, where a diamond is held when set in jewelry.
- Depth: The height of a gemstone, from the culet to the table. Determined as a percentage of the overall diameter of the gem.
Color refers to the natural body color of a diamond and not to the reflection of spectral colors that flash when a diamond moves. Most diamonds naturally exhibit slight hints of yellow, brown, or gray. This color is caused by natural trace elements of nitrogen that were present when the diamond formed under the Earth’s crust. The less color a diamond exhibits, the higher the rarity, and therefore the higher the value. After cut, color is the next most important characteristic to consider when choosing a diamond.
Diamonds with less color allow more light to pass, releasing more brilliance and fire. A diamond acts as a prism by dividing light into a spectrum of colors and reflecting this light as colorful flashes called dispersion or fire. Similar to looking through colored glass, color in a diamond will diminish the spectrum of color, or fire, emitted by acting as a filter. A diamond with a higher color grade, i.e., one with less color, demonstrates more colorful fire.
- D: Absolutely colorless or "icy white". The highest color grade, extremely rare and most expensive.
- E: Colorless. Only miniscule traces of color can be detected by an expert gemologist in a controlled environment, a very rare diamond.
- F: Colorless. Slight color detected by an expert gemologist, but still considered a colorless grade, a rare, high quality diamond.
- G-H: Near-colorless. Color may be noticeable compared to diamonds of better grades, but offers excellent value.
- I-J: Near-colorless. Color slightly detectable when compared to diamonds of better grades, a good value.
Clarity refers to how clean or clear the diamond is with respect to natural microscopic characteristics that were trapped within or on the diamond while it was forming. Internal characteristics are known as inclusions, and characteristics on the surface of the gem are known as blemishes. Inclusions may be crystals of a foreign material or structural imperfections such as tiny cracks, known as feathers, which can appear whitish or cloudy. Often times the inclusions are microscopic diamonds that were absorbed by the larger crystal before the diamond was carried to the surface of the Earth. The quantity, size, color, location, orientation, and visibility of inclusions all affect the final clarity grade of a diamond. Diamonds with no or few inclusions are considered particularly rare and highly valued.
When gemologists inspect diamonds for clarity, they use a maximum of 10x magnification and only judge the diamond face up. If an inclusion is not visible when the diamond is viewed from the top, then it cannot be used in determining the clarity grade. Gemologists use microscopes and loupes (small handheld magnifying lenses) to determine the size, type, and position of the inclusions.
Experienced graders use 10X magnification to identify the various clarity characteristics, and to map their location on “diamond plots.” These plots are like small maps for each individual diamond, and are used to identify each individual stone. No two diamonds will ever have the same internal pattern, and the plots work as a form of individual identification much like a fingerprint.
Clarity grades applied by expert graders are as follows:
Carat (ct.) refers to the unique unit of weight measurement used exclusively to weigh gems and diamonds. Carat weight is often confused with visual size even though it is actually a measurement of weight. Depending on the shape and type of gemstone being weighed, the weight will visually show itself differently. For example, a 1.00 ct. round diamond will measure around 6.5mm, and a 1.00 ct. round sapphire will measure around 6.0mm. This is due to the varying density of different gemstones.
Once cut, color, and clarity grade have been determined, the carat weight of a diamond can be easily established to fit within a budget. Larger diamonds are much more valuable because they are discovered in nature much less frequently than small ones. Diamond prices actually rise exponentially with carat weight rather than linearly. For example, a 1.00 ct. diamond of a given quality is always valued higher than two 0.50 ct. diamonds of the same quality. In fact, a general rule of thumb is that a diamond of double the weight costs around four times more.
“Under-sizes” are diamonds that weigh just below a cutoff weight. While fewer exist, they may represent an enhanced value. They are more difficult to find as a diamond cutter will choose to sacrifice beauty in order to cut a diamond with a weight that reaches one of the cutoff weights, or “magic numbers” as they are known in the industry. The cutoff weights are 0.50 ct., 0.75 ct., 0.90 ct., 1.00 ct., 1.50 ct., and 2.00 ct.
Total carat weight (t.c.w.) is a phrase that represents the total weight of all diamonds or other gemstones in a piece of jewelry, when more than one gemstone is used. Diamond solitaire earrings, for example, are usually quoted in t.c.w., indicating the combined weight of the diamonds in both earrings.
