Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal characteristics called inclusions and external characteristics called blemishes or "birthmarks".
Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these characteristics, as well as how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value. Inclusions in the diamond sometimes make for "true masterpieces". Some diamond inclusions can be work of art on their own and additionally increase the price of the Diamond!
Like the color scale, GIA’s clarity grading system developed because jewelers were using terms that could be misinterpreted, “loupe clean” or “piqué.” Today, even if you buy a diamond somewhere else in the world, the jeweler will most likely use terms like VVS1 or SI2, even if his or her language is French or Japanese instead of English.
Small crystals can become trapped in a diamond when it’s forming. Sometimes as a crystal grows it can develop irregularities in its atomic structure. Diamond inclusions are among the important factors influencing the appearance and consequently the pricing of a diamond! Nobody wants to have a diamond with visible imperfections. Furthermore, nobody would like to have a diamond with inclusions that pose a durability risk!
Evaluating diamond clarity involves determining the number, size, relief, nature, and position of these characteristics, as well as how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value.
Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the GIA International Diamond Grading System™, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3). Every diamond is absolutely unique and none is absolutely perfect under 10× magnification though some come close. Known as Flawless diamonds, these are exceptionally rare. Most jewelers have never even seen one.
The GIA Clarity Scale contains 11 grades, with most diamonds falling into the VS (very slightly included) or SI (slightly included) categories. In determining a clarity grade, the GIA system considers the size, nature, position, color or relief, and quantity of clarity characteristics visible under 10x magnification.
Laser Drill Hole - A laser drilled holes are permanent in their nature and will thus be graded by GIA. If, however, the drill hole on the surface can not be made out easily, instead of the “Laser Drill Hole” mark you will find in the comments section note “Internal laser drilling is present”. Any laser drilling of the diamond is irreversible, thus must be disclosed by the seller, as a laser drilling severely affects the price of the diamond.
Crystal - A crystal inclusions can come in various shapes and colors. Colors variations depend on the specific mineral that is trapped within the diamond. White crystal inclusions are usually a tiny diamond crystal trapped inside of the diamond. If they are not too big, the white crystals will not be visible to the naked eye. Other notable crystal colors would be: black - Carbon or Graphite; red - Garnets; and very rarely green - bits of Peridot entrapped in the Diamond. Crystal inclusions, in an eye clean diamonds, are usually too small to pose a serious durability risk to the stone.
Needle - Extreme pressure applied to the diamond as it is forming causes the crystals to appear as a long, thin needle shape rather than the more common circular shape. Needles are crystals that look like tiny rods at 10X. Often very small, white or transparent in color, needles are not usually visible to the naked eye, unless they are of a distinctive color. If needles appear in clusters, they might have a detrimental effect on the diamond’s clarity and pricing.
Pinpoint - Pinpoints are very small white or black crystals that look like a tiny dot at 10X. are embedded inside a diamond. Individual pinpoint inclusions do not usually affect diamond clarity. However, when three or more pinpoints are in a concentrated area, they form a cloud. Clouds may affect a diamond's clarity, depending on the number and color of the pinpoints in the cloud.
Cloud - A cloud inclusion is a broad term used to characterize a cluster of pinpoints/crystals, white black or transparent, found very close to each other. In essence, those are many tightly grouped pinpoints that might be too small to distinguish individually however, they look like a white or gray patch in the diamond. Clouds can give the stone a hazy appearance and negatively affect how the light travels through the diamond.
Twinning Wisp - A series of pinpoints, clouds, or crystals that form in a diamond’s growth place, which may be light or dark in color. Essentially that's an intergrowth within the diamond, which has twisted together within a twinning plane. At high magnification, twinning wisps often look like white or black stripes or streaking within the diamond. Twinning wisps are not necessarily "bad inclusions", but they need to be carefully evaluated to determine whether they affect visual performance of the stone in question.
Knot - A knot is an included white or transparent diamond crystal, more like a smaller diamond within the larger diamond, with their own growth patterns that may not follow that of the actual diamond. A diamond knot occurs significantly less often than other more common inclusions like pinpoints, needles or feathers. Nevertheless, the presence of a knot can be much more problematic. Knots, which appear close to the diamond surface can extend all the way to the surface after fashioning, thus affecting severely the quality of the diamond.
Feather - Feather is a general trade term for a break in a gemstone. Depending on the viewing angle they are often white and feathery in appearance. Feathers can be transparent and almost invisible, but nevertheless, they are small cracks or fractures within the diamond. Severe feathers can cause durability issues, especially if they are reaching toward the surface or are located near the girdle area.
Chip - A shallow opening caused by damage to the stone’s surface that typically occurs at a girdle edge, facet junction, or culet. This inclusion type is typically man-made in the sense that it is caused by wear and tear or accidental knocks.
Cavity - Cavities are usually created during the polishing process when an internal inclusion like a crystal falls out of its pocket. In essence, an angular opening created when part of a feather breaks away or when a surface-reaching crystal drops out or is forced out during polishing. This usually takes the form of a large or deep opening/dimple on the diamond’s surface.
Bruise - Diamonds subjected to a blow or a hard knock as they are forming are likely to get bruised. A "bruise" is a tiny area of impact accompanied by very small, root-link feathers; typically bruises occur at a facet junction. Bruises can be any size and can occur in any place on the surface of the diamond, although they are often found in the diamond crown.
Indented Natural - A portion of the rough diamond’s original surface, a “flaw” which dips below the polished diamond’s surface. An indented natural is a part of the rough diamond, that the cutter is forced to leave untouched during the polishing process and is usually found at the girdle. An indented natural is only considered "an inclusion" because it does extend below the surface of the finished stone.
Natural - These refer to parts of the original surface of the diamond, which has been left alone and unpolished. Naturals are usually left on or near the girdle of the diamond. While these are considered blemishes, the presence of naturals is a sign of good cutting practice, where the cutter has managed to retain as much of the original weight as possible. In positions near or at the girdle, the natural is not visible even under 10X. Naturals can be removed if the cutter polishes out the area more roughly. However, this would result in a drop of the diamond's weight by up to 25%.
Extra Facet - That is a "man-added flaws” made on a diamond. These are not "mistakes". Believe it or not, mistakes rarely occur during the process of diamond cutting. These are deliberately cut to remove imperfections at/or close to the very surface of the stone. At times these extra facets are also cut purposely to enhance the brilliance of the diamond. Extra facets are usually added to specific locations, by design and intentional purpose and do not necessarily affect the clarity grade of a diamond.