Clarity is among one of the Four Cs used to evaluate the quality and determine the value of a diamond. The term 'clarity' denotes the absence of inclusions and blemishes on a stone. Inclusions are internal, while blemishes are surface defects. Clarity affects a diamond's beauty and its performance in terms of brilliance and durability.

The Gemological Institute of America (GIA) developed a clarity grading scale, widely used in the industry:

Flawless (FL):

• No inclusions or blemishes visible under 10x magnification, extremely rare and valuable.

Internally Flawless (IF):

• No inclusions and only minor blemishes visible under 10x magnification, quite rare.

Very, Very Slightly Included (VVS1/VVS2):

• Inclusions are so slight they are hard to detect under 10x magnification.

Very Slightly Included (VS1/VS2):

• Inclusions are minor and observed with effort under 10x magnification.

Slightly Included (SI1/SI2):

• Inclusions are noticeable under 10x magnification and may affect brilliance.

Included (I1/I2/I3):

• Inclusions are obvious and affect transparency and brilliance.

Factors affecting clarity include the size, number, location, and type of inclusions. High-relief inclusions are more visible and impact the clarity grade more significantly.

Though higher clarity grades are more desirable and valuable, many inclusions and blemishes are not visible to the naked eye. Diamonds in the VS and SI range can offer good value, as their inclusions are often invisible without magnification, making them a beautiful choice at a more accessible price point.

In conclusion, diamond clarity is crucial in selecting a diamond as it impacts the stone's appearance, value, and sometimes durability. However, it should be balanced with other factors like cut, color, and carat weight to find the best diamond within one's budget.