Diamond Clarity is a measure of the amount and visibility of imperfections in the diamond. This is gradeded on a scale from FL to I3 (Fl-Flawless, IF-Internally flawless, VVS1/2-Very very small inclusions, VS1/2- Very small inclusions, SI1/2- Slight inclusions and I1/3- [heavily] included). Anything above and including SI clarity will have small inclusions but these will all be invisible to the naked eye, even a trained gemologist will not be able to see inclusions without magnification.

Furthermore, inclusion does not really affect light performance in the diamond, even at I grading it is minimal, but with SI and above there will be no impact on the light performance of the diamond. A I rating (often called PK) will look, frankly, awful however due to the level of inclusions and their clear visibility from the naked eye.

The clarity rating you choose depends on your budget and which of the four c’s you intend to focus on more closely, if for example cut is your main concern, then you may want to downgrade your clarity rating in order to be able to increase your cut. If you do decide to trade off a higher cut grade for another of the four c’s then please ensure you do not go lower than SI2, as below this imperfections will be easily seen and the apperance of your diamond will be ruined. It is no good having a 1 carat PK2 because while it may be big, it will not look good.

Diamond cut is arguably the most important on-certificate (that is it is graded by the grading labs and is not to do wtih rough diamond quality), because an excellently cut diamond will reflect light better (increasing it’s brilliance and scintillation), and refract light better (increasing it’s fire) than a poorly cut diamond.

Diamond cut is usually graded on a scale ascending from poor to excellent (poor, fair, good, very good, excellent), but, often in diamond sales names such as premium or ideal will be used ,these are however, never used on diamond certificates.  Cut is a average of the angles of the diamond facets, but because it is an average there is room for deviation. For example, if we assume 41° is the perfect angle then we could theoretically have one facet at 41.2° and another at 40.8°.  When averaged these angles would give a result of 41° (our assumed ideal) when in fact they are not perfect and therefore would not give optimum light performance.

This is where Hearts and Arrows comes in, because a diamond with Hearts and Arrows will have perfect optical symetery, meaning that all facet angles are equal and when combined with an excellent cut, i.e. they have an average facet angle of 41°(40.8° is actually the European ideal pavillion angle) the addition of Hearts and Arrows would ensure that every angle in the pavillion was 41°; ensuring a truely perfect cut.

For more information on diamond cut please watch: