Clarity

The clarity of a diamond refers to the amount of visible flaws in the diamond. The fewer the visible flaws, the more expensive the diamond. 

Flaws that are visible on the surface of the diamond are called blemishes. Flaws that are visible inside the diamond are called inclusions.

NB: Stones are what diamonds are called within the diamond trade.
A loupe is a small magnifying glass that is held up to the eye.

There are many terms used to describe the types of flaws that can occur in diamonds. Some of common ones are:

Crystal (internal)
A crystal is any mineral crystal that is enclosed by the diamond. They can also occur on the surface of a diamond. They can be any size, shape or colour but the most common ones appear like a small clear bubble to the naked eye. They are sometimes referred to as "carbons”, “carbon spots” or “bubbles”.

Feathers (internal)
A feather is any type of break or fracture in a diamond. They often have a feather-like appearance, hence the name. A heavy knock to the diamond can make them larger.

Pinpoints (internal)
A pinpoint is a type of crystal that is very small and cannot be seen by the naked eye, only with a 10x or greater magnification.

Clouds (internal)
A cloud is a very tightly packed group of pinpoints that looks like a cloud under 10x magnification.

Abrasion (external)
An abrasion is a series of very small nicks or chips on the surface of a diamond, usually along a facet line. These are caused by wear and tear when diamonds are not stored carefully with other diamonds (as only diamond can scratch diamond).

For a more detailed coverage of the various types of flaws, including photos, please visit:

http://www.diamondsourceva.com/Education/Clarity/diamonds-inclusions-blemishes.asp 

Each time you view a diamond, have the jeweller show you the flaw diagram on the laboratory certificate and ask him to point out these flaws on the diamond itself. If the diamond has good clarity it may be difficult to see these flaws but persevere, once you have seen the most common types of flaw once, it will become easier to find them on other diamonds. 

Tips on Diamond Clarity

When assessing a diamond’s clarity: 

• ALWAYS use at least a 10x magnification eyepiece (known as a loupe in the industry). If you use a lower magnification you may not pick up all of the important flaws in the diamond.

• Always view the diamond un-mounted. If the diamond is already mounted in a ring, the mounting claws and the mounting itself may obscure any flaws.

• Always buy a diamond with an independent laboratory certificate. The flaw diagram on the laboratory certificate will be marked with the locations of the flaws that were identified when the grading was performed. The flaws are a great distinguishing feature of each individual diamond. They can be a good means of assuring yourself that the diamond you are viewing is actually the same diamond that is graded on the laboratory certificate, and that a "switch” of diamonds hasn’t taken place.