Sorting and Valuation
In nature there are no perfect crystals, or two identical diamonds. Therefore, grading of diamonds involves sorting them by more than 8,000 sorting criteria.
Each diamond crystal is described according to four major grading characteristics: carats (weight or size), cut (shape), clarity (quality), and color.
Until the middle of the twentieth century, there was no agreed-upon standard by which diamonds could be judged. GIA created the first, and now globally accepted standard for describing diamonds: Color, Clarity, Cut and Carat Weight. Today, the 4Cs of Diamond Quality is the universal method for assessing the quality of any diamond, anywhere in the world.
shape
Each diamond shape has its own unique characteristics and is cut to different specifications, which impacts the overall look of the stone. Some diamond shapes are cut to optimize light return. These are referred to as brilliant cuts, and include round, princess, cushion, marquise, oval, radiant, pear, and heart shaped diamonds. The facets on the pavilion, or underside, of these diamonds meet at a point, which ensures maximum light return. Other diamond shapes are cut to highlight the clarity of the diamond. These are referred to as step cuts, and include asscher and emerald shaped diamonds. These shapes feature parallel facets on the pavilion, which offers a subtle shimmer while accentuating clarity.
Diamond shapes
cut
The cut of a diamond refers not to its shape, but to the balance of proportion, symmetry and polish achieved by the diamond cutter. The extent of how well the diamond is cut is directly related to the diamond’s overall beauty. When a diamond has been correctly cut, the diamond’s ability to reflect and refract light is greatly enhanced. By understanding the way that light moves through diamond crystals, modern diamond cutters have established a specific set of proportions and angles that are known to harness the diamond’s internal brilliance and to show it in its best light.
Diamond cut scale
color
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.
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.
Diamond color scale
clarity
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.
Diamond clarity scale
carat
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.
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.
Diamond carat scale
