Because diamonds are formed under extreme pressure deep within the earth, virtually all diamonds have a birthmark called inclusions. Diamonds are after all a product of mother earth and were created over a period of thousands of years. The lesser the inclusions are, the more valuable the diamond becomes. The levels of inclusions are:

		Internally Flawless (IF) No inclusions are visible to a skilled grader at 10x magnification.
		Very, Very Small Inclusions (VVS1, VVS2) Minute inclusions are extremely difficult for a skilled grader to see at 10x magnification.
		Very Small Inclusions (VS1, VS2) Minute inclusions are difficult for a skilled grader to see at 10x magnification and still are invisible to the naked eye .
		Small Inclusions (SI1, SI2, SI3) Inclusions are visible under 10x magnification and might be visible to the naked eye particularly in the case of SI3.
		Inclusions  (I1, I2, I3) Obvious inclusions are visible to the naked eye and may affect transparency and brilliance