In order to determine the clarity of a diamond, you'll need someone with a trained eye to view it under 10-power magnification. The smaller and fewer the inclusions, the more able light can pass through the diamond, contributing significantly to its rare beauty. More than any other gemstone, diamonds are capable of producing the maximum amount of brilliance. Thus a diamond which is free of inclusions and surface blemishes is more rare and, by definition, more valuable.
External flaws are the result of wear and tear on the diamond or from damage caused during cutting.
There are many kinds of internal flaws. Clouds, are microscopic inclusions that lower transparency. Inclusions and external blemishes easy to locate with naked eye. Heavy inclusions located with naked eye. As a rule of thumb two months salary is standard, however more or less is also fine.