Here is a list of diamond flaws. It is a good idea become familiar with these as they can help in identifying diamonds.
Diamond flaws are, in fact, quite common. Most are not perfect and usually consist of either an inclusion or an imperfection.
Inclusions are always classified in the manner they were formed. Some were formed when the diamond was made these are called syngentic diamond inclusions. Others are formed some time afterwards. These are called epigenetic diamond inclusions.
The list is in alphabetical order.
These are flaws found on the surface as distinct to those inside the diamond.
Blemishes are flaws which can be caused either naturally or, more commonly, as a result of the environment such as when the diamond is being cut and polished for example.
As diamonds are made from carbon it is bound to happen that diamonds may occasionally have carbon flaws in them.
During the formation of a diamond sometimes the diamond does not form fully resulting in not crystallizing and then resulting in the presence of small black carbon deposits on them. Carbon flaws can affect the clarity of the stone depending on how big or small they are. These are not common occurrences compared to, say, pinpoint inclusions and when they are it is usually only in the white or blue-white stones. Carbons are not, curiously enough, commonly found in diamonds of poorer colors.
Where breaking off of a small piece of diamond towards the surface is usually referred to as chipping, this should not be confused with 'diamond chips', which are very small pieces of individual diamonds. Chips are usually caused by minor impact or impacts from the environment. A downward impact occurring when a stone is being set or is being worn, can cause chips on the culet of the diamond. As these are commonly caused when a diamond is worn, it is suggested that while diamonds are being set, a little space be left between the base of the diamond and the head of the prongs of the ring. This space acts as a cushion protecting the diamond from possible chipping when it falls. Chips are easy to remove by treating the diamond.
Larger chipping in diamonds can lead to a diamond cavity. This term refers, then, to the presence of a large or deep opening in a diamond. These can be caused when a diamond cutter has removed a large crystal inclusion close to the diamond surface. It is very rare.
These are usually cut to remove blemishes or certain close to surface inclusions on diamonds. Sometimes these extra facets are cut to enhance the brilliance of the diamond and do not usually affect the clarity grade of a diamond.
Any breakage in diamonds that is not parallel to the cleavage plane is referred to as a fracture. Fractures are usually irregular in shape making a diamond look chipped. Diamonds with fractures will commonly be 'fracture filled' to improve the diamond clarity of such diamonds. It does not improve the value however so should be looked for when buying a new diamond.
You can sometimes, albeit rarely, find fingerprint inclusions in the shape of fingerprints in diamonds. These are more common in other stones such as rubies and emeralds for example. These inclusions are formed during a fluid assisted partial healing of fractures already present in the stone. For this to take place in diamonds, high temperatures and pressures (HTHP) are required, so it is somewhat unusual. Until recently, few such flaws have been reported in natural blue and colorless diamonds. This could indicate that diamonds have been HTHP treated but, giving the required temperatures for fingerprint inclusions, this is not always the case. The earth can also cause geologically high temperatures, leading to the formation of fingerprint inclusions.
Pits are small holes on the surface of a diamond. They are not usually visible to the naked eye except for pits on the surface table facet can be pits are usually not visible to the naked eye. However, pits present on the table facet of a diamond are usually visible and can reduce the clarity of a diamond.
Now this refers to the original surface of the diamond which has not been polished and has been left as is. Naturals are usually left on or near the girdle of the diamond. While these are considered as blemishes, the presence of naturals is a sign of good cutting practice, the purpose being to retain as much of the original weight as possible. Indented naturals can also be seen to exist on some stones. Here the portion of the natural is seen to dip inside slightly from the diameter of the stone. The cutter usually leaves the indented natural either at the girdle or pavilion of the stone, in order to keep it less noticeable. In such positions, the natural is not visible even with a loupe. Indents can be removed if the cutter polishes out rougher. However, this can result in a drop of the diamond's weight by up to 25 percent.
Nicks are similar to chipping. Diamonds can be chipped at places causing the appearance of nicks, usually due to rough treatment. Diamonds may be the hardest substance but it can still be shattered. Nicks can often repaired by adding extra facets. It should be kept in mind that too many facets, however, can reduce the brilliance of a diamond and should be avoided.
Fine lines found on the surface of the diamond. Usually created when the diamond was being cut. Small minor scratches can usually be polished off but deeper ones will involve treating the diamond.
Virtually every natural diamond crystal contains impurities and internal defects: such as vacancies, dislocations, and interstitial atoms. The most common impurity in diamond is nitrogen, which can comprise up to 1% of a diamond by mass. Nitrogen as a diamond impurity was first identified in 1959 by Kaiser and Bond of Bell Telephone.
This is also known as girdle fencing or 'dig marks', and this can be caused around the diamond's girdle as the diamond is cut or bruited. When you insect them, these fine lines can be seen to resemble a hair strand and do not present a problem. Extensive bearding, however, can lessen the brightness of the diamond.
This type of cleavage has nothing to do with a woman's bosom but are cracks in a diamond that occur in a straight line and are parallel to one of the diamond's crystallographic planes. Cleavages are generally usually caused by a deep internal strain in a diamond. They can also be caused by a strong blow on the diamond and has a high chance of causing the stone to split, especially if placed in the high pressure grip of prongs in rings. Stones with cleavage should be chosen very carefully.
A cloud is simply three or more pinpoint inclusions close enough together to give the impression of a 'cloud' within the diamond. usually a small cloud is not visible to the naked eye, but the presence of so many pinpoints covering a large area can affect the clarity of the diamond. These are usually indicated on grading reports in the form of tiny red dots close together or as circles and other formations so should be watched for.
Some diamonds will show the presence of small crystals, minerals or other diamonds. These will be classified in various categories depending upon the size and structure of the inclusion. While most inclusions of this type are small and not visible to the naked eye, some diamonds may have larger inclusions which can be seen with the naked eye and can affect a diamond's clarity and also, incidentally, its life. Some crystals take on shapes of bubbles, needles or grains and are classified as under.
These are cracks in the stone that resemble the design of feathers. Presence of this in a diamond usually does not affect the life of the stone unless and until the feather runs through a major length of the stone or shows major stress points where it can break. If the cracks reach the surface or have deep fissures, the durability of the stone may be reduced with the possibility of the stone breaking with age.
Crystal inclusions in diamonds can also occur in the form of lines, known as grain lines. These are usually formed due to improper crystallization of the diamond, when it was being formed. Grain lines can also be caused due to improper polishing of the diamond. Even skilled diamond cutters may come across diamonds with variations in hardness when a facet is polished. This can cause microscopic lines across the facet. These grains are usually difficult to remove without excessive weight loss. Grain lines are commonly seen in pink fancy diamonds. A saturation of grain lines on pink stones can also make them look red.
Twinning wisps or intergrowths may also be seen in diamonds. These formations are usually inclusions in diamonds that have twisted together during the time of diamond formation. Thus various inclusions like pinpoints, needles or feathers may form together creating a white strip inside the diamond. Surface graining may also be seen in some cases. Such intergrowths are more commonly seen in fancy shaped diamonds and are extremely rare in ideal cut diamonds.
When diamond crystals extend to the surface of the diamond, they are referred to as knots. These can be viewed under proper lighting conditions with a diamond loupe. Certain knot formations may also cause raised areas on particular facets of the diamond. The presence of knots may affect both the clarity and durability of the diamond and are best avoided.
Diamond crystals in a diamond can also be present in the form of long and thin needles. These may not be visible to the naked eye, unless the needle inclusion is of a noticeable color or has a noticeable presence. Some needle inclusions are known to give diamonds a special look too.
The last to be mentioned but probably the most common diamond flaws are the small pinpoints of light called pinpoint inclusions. As the name implies, these inclusions are minute crystals usually white in color present inside the diamond. Most pinpoint inclusions do not affect the clarity of a diamond and, in fact, are not even visible to the naked eye and usually not indicated on the plotting diagrams of diamond reports. Comments such as pinpoints not shown may often be listed in the comments section.
Diamond flaws are not necessarily a bad thing. A diamond flaw can not only lend a distinct beauty but also a uniqueness and individuality no other diamond has. This then also helps to establish the authenticity of a diamond and gives it its own unique fingerprint.