Needles
| Long and thin needle-shaped crystals can be present in a diamond. They may not be visible to the naked eye unless they are of a conspicuous size or color. If needle inclusions appear in clusters, they might even affect a diamond’s clarity. |
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Cloud
A diamond can have a hazy area or what is known as a “cloud.” This type of aggregated flaw requires the presence of three or more pinpoint inclusions close together. A small cloud may not be visible but many pinpoint inclusions causing a haze can affect a diamond’s clarity. Grading reports indicate such flaws through the use of circles or small red dots set close together.
Knots
Knots are diamond crystals that have reached the surface of the diamond. These inclusions can be seen with a diamond loupe and may cause the existence of raised areas on one or more diamond facets. Knots should be avoided as they can affect a diamond’s clarity and durability.
Cleavage
A crack that occurs in a diamond that travels in a straight line and runs parallel to one of the diamond's crystal lattice planes is called a “cleavage.” Produced by deep internal strains in a diamond, cleavages can cause the diamond to split, especially if the stone is stressed during the mounting process by the prongs of a ring. Diamonds that contain a cleavage must be handled carefully or not used at all.
Feathers
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Some cracks in a diamond may resemble feathers. Feather-like inclusions in a diamond, unless they run for a good distance through the stone or display major stress points where the stone can break, usually do not affect the life of the stone. If the feathers reach the surface or have deep crevices, the diamond’s durability may be compromised and the stone may break in time. |
Grain Lines
Grain lines are linear crystal inclusions. If a diamond is subjected to improper crystallization at the time of formation, grain lines can result. Another cause of grain lines is the improper polishing of the diamond. Some diamonds may have variations in hardness and when faceted and polished these microscopic lines may manifest themselves by extending across the facet. To remove these flaws, the diamond will have to be reduced in size. Grain lines are common in pink fancy diamonds and can even change the color of a stone.
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