Diamond Blemishes are external flaws that appear on its surface.
These flaws are mostly caused by improper cutting process or due to
mishandling of diamond and are not present in all natural diamonds.
Blemishes have quite an effect on the clarity of diamond which lowers the value of diamond.
Types of Blemishes
Following are the examples of diamond blemishes or external flaws in different categories:
Abrasion is result of mishandling of jewelry. It is caused when jewelry is kept in such manner that diamonds rub against each other. It’s actually group of very tiny nicks on the edge of facet. Abrasion gives facets’ edge dull and fuzzy look.
Burn marks are caused when diamond is polished vigorously. The heat generated due to continuous rubbing makes the diamond surface appear cloudy. It may also result when jewelry is exposed to heat on daily basis like diamond set in ring. These marks can be removed by proper polishing.
Extra facets appear when the rough crystal is not cut in symmetrical manner. This happens when diamond cut to remove minor blemish like natural or nick. Extra facet does not affect the clarity of diamond.
It’s often seen that diamond with "Flawless" clarity have extra facets which are formed when diamond is cut so that inclusions and blemishes can be removed to attain high clarity and enhance the brilliance of diamond.
Natural is a portion of original rough diamond crystal which is left unpolished. It’s normally found on or near girdle. The original skin of diamond might have growth lines, which are triangular in shape. This texture is visible when viewed from 10X magnifying lens.
The difference between naturals and indented naturals is that an indented naturals extends onto the crown or pavilion.
Nicks are small chips on the surface of diamond. It’s result of mishandling of jewelry or when the jewelry undergoes excessive wear and tear in day to day life. Generally it occurs along girdle or on edge of facets.
Nicks can affect the durability of your diamond as any further mechanical stress can increase nicks causing diamond to crack. Nicks can be removed by re-polishing and adding extra facet.
It usually occurs when pinpoint inclusions are removed from diamond’s surface while polishing. It can be referred as small white dot or tiny cavity. It can be viewed through 10X magnifying lens and if present on table of diamond it affects the clarity of diamond.
Rough girdle refers to girdle that has irregular, pitted, chipped and granular surface. It appears bearded and has hazy and dull look. It’s advised to avoid diamonds with rough girdle as not only you can see it through naked eye but you can feel the rough surface.
Scratches are thin fine lines on the surface of diamond. They occur naturally or may be the result of defects while cutting process. Loose diamonds meant for trading are kept in the fold over diamond papers, because if not handled carefully it can result into scratches.
Scratch can also result if jewelry is not stored properly and one piece of jewelry touches other or if different pieces are kept on each other.
Minor scratches can be removed through polishing. Diamonds having large scratches should be avoided as these flaws reduce the clarity of diamond.
Surface grains or lines occur due to irregular crystallization during formation of diamond. Grains are present in all diamonds.
If grains are transparent and small in number then these does not affect diamond’s clarity. When present in large clusters, it can be seen by naked eye. As grains do not affect clarity of diamond it’s not included grading report but mentioned in comment section of certificate.
Twin Lines/Knot Lines
Twin lines or Knot lines result due to presence of large crystal inclusion whose orientation is different from the main crystal. You should keep in mind that it is different from crystal growth lines as these lines appear on surface of diamond while crystal growth line are present within the diamond.
Wheel Marks are the groves formed due to rough grinding process during diamond polishing. Ideally, these flaws should be removed in final phases of polishing, but due to inexperience of cutter grooves may remain behind on diamond surface. Wheel Marks affect the clarity of diamond and cause diffraction of light.