Clarity is one of the four factors that determine the worth of a diamond. Clarity is the measure of imperfections, some of which (inclusions) occur naturally in nature and some (blemishes) which can be a result of the manufacturing process. Inclusions are normal and are in most diamonds unless the diamond is graded flawless, but these are rare and expensive. Diamonds with the least or the smallest inclusions have higher clarity grades and vice versa. The clarity directly impacts the brilliance and shine.
A diamond graded SI1 or above is ‘eye clean’ meaning that any inclusions are too small to see with the naked eye and require magnification. SI2 have some visible marks but these aren’t necessarily visible except upon close inspection. Diamonds can be graded flawless or internally flawless which is rather self-explanatory, these are also incredibly rare. VVS1 & 2 are diamonds that are very, very slightly included, these are of excellent quality and it’s hard to see inclusions even under magnification. VS1 & VS2 have imperfections visible under magnification and are also of high quality but are less expensive. I1, I2, & I3 have significant flaws, quick glances can overlook these, they are more obvious even to the unaided eye.
There are many different types of flaws that can appear. Crystals are the mineral spots that can appear, the two most common are white and black, white being the best because they can blend in, black can end up looking like dust. Pinpoints are tiny crystals; they are almost impossible to detect. Clouds are a cluster of pinpoints that combine to look like one larger flaw they can be more noticeable and make the diamond look hazy. Long thin crystals are called needles and are usually white. Feathers are internal cracks, if located near the edge it can make the diamond more susceptible to chipping.
Graining is caused by an abnormal growth in the crystal structure, either internally or on the surface. Twinning wisps are also caused by an irregular growth in the structure, usually a group of another inclusion such as clouds or feathers. A cavity is obviously a small hole or void, a chip is a surface blemish, polishing lines, scratches and bearding are all manufacturing errors. Bearding is the very small fractures or feathers along the girdle, this happens when too much pressure is applied.
When diamonds are formed, under intense pressure and heat deep underground, these imperfections in the structure or mineral impurities can become trapped inside. Inclusions are solids, liquids and gasses, they can be crystals made of foreign materials or even other diamond crystals. The number, size, colour, location, and visibility all affect the clarity. However, inclusions can serve a purpose; they are used as identifying marks similar to fingerprints – they can also speak to the origin of a diamond whether it was natural or synthetic. This is a brief overview, more research would be needed for the best diamond clarity information.