Diamond crystals have been present in and on the earth’s surface for millions of years. As they were being formed through the heat and pressure being exerted on the continental plates, most developed unique characteristics inside each of these crystals. Today, we call these fissures, cracks and other assorted characteristics, marks or material inside or on the surface of a diamond crystal, inclusions or blemishes.                                                              

These inclusions or blemishes have been categorized in a variety of ways to reflect the not only the size and number of them, but also their color, position and the extent of their visibility with or without magnification. While these inclusions and blemishes usually have little bearing on the strength or integrity of the diamond, in some cases depending on size and position, they can cause the diamond to fracture more easily.

These inclusions and blemishes are considered imperfections in a diamond and while some larger imperfections may be seen by the naked eye, many can only be seen with the use of and under 10X power magnification. Each diamonds imperfections are unique to that particular stone and can be used to identify the diamond and authenticate the natural and not synthetic origin of the stone.          

Beginning in the early 1950’s, the Gemological Institute of America began grading diamonds using a new standard to define the clarity of a diamond. Using 10X power magnification as its method of observation it defined the different types of inclusions and blemishes found inside and on the surface of the diamond, and assigned words and numbers to equate with the size, amount, type, place and color of the imperfections found in or on the diamond.

Diamonds not possessing any of these imperfections or “flaws” under 10X power magnification were considered “flawless”. The next level of imperfection was considered very, very, slight and was thus labeled VVS1 or VVS2, based on the very slightest of difference as to where and type of imperfection found in the stone. The next level of imperfections were considered slightly stronger that those found in the VVS category and were labeled very slight or VS1 or VS2. Following this category were the next levels of imperfection, slightly imperfect or SI1 and SI2. These imperfections were yet again considered stronger than those found in the VS category.  

It is important to recognize at this point, that unlike color, which can be seen and judged immediately, clarity in any of these categories which have just been explained, absolutely cannot. In most cases, to the naked eye, there is no difference in the appearance of a stone categorized as Flawless or as one characterized as SI2 assuming color, cut, and carat are the same. 

Following the slightly imperfect or SI level, those diamonds with stronger imperfections, those that perhaps can be seen by the naked eye without the help of 10X power magnification are categorized as imperfect or I1 and I2.  In recent years the word “imperfect” in the definition of each category has been changed to the word “included” and an additional category of I3 has been added. In almost all cases those diamonds categorized as I2 or I3 have strong enough imperfections or inclusions to be seen by the naked eye. 

While the level of imperfection in or on the surface of a diamond can have as significant an impact as differences in color on the cost a diamond, only the strongest of imperfections or inclusions will change the look luster or sparkle of that diamond. The cut or make of the diamond is however, another story.