Clarity is a broad term, traditionally used to define the quality of a polished diamond on the basis of the presence of inclusion (internal) or blemishes external flaws in a diamond under 10x magnification which to great extent determines its appearance and in turns its value.


RGS provides clarity grades from FL to I3--, whereas the other grading systems consider only 12 clarity grades. This is due to the addition of 'better (+)' and 'lower (-)' grades between the standard clarity grade (for e.g. :- SI1+, SI1 and SI1-), resulting in significantly enhanced precision detailing as well as pricing.

Apart from the FL to I3-- category of clarity grading, there are certain other factors which makes any particular clarity either alluring or unappealing. For example a centre clears SI3 clarity stone with scattered white inclusion can be more appealing than a SI2 stone with black concentrated inclusion, reason as such has compelled to consider certain other factors while considering the price of the stone. The other such factor which can be concluded in the clarity factors are as follows:

Under RGS, table inclusion is primarily the amount of inclusion Visible in the table area and the quantum of impact it has in context to the clarity of the stone.

Here at RGS table inclusion is graded in two parts –

  • Firstly, the overall impact of table inclusion in context to other inclusion present in the stone on the purity of the stone.
  • And secondly, the percentage of black inclusion present in the table inclusion.

Both are graded as N, V, S, M and H with a total combination of 21 grades. The first letter will indicate the percentage of inclusion affecting the clarity of the stone visible from the table area, and the second letter will be indicative of the percentage of black inclusion visible from the table area taking the table inclusions as the base.

Image Grade Description
NN No inclusion visible from the table either black or white
VN Less than 25 % inclusion affecting clarity visible from table area and none of it is black
VV Less than 25 % inclusion affecting clarity visible from table area and less than 25 % of it is black
VS Less than 25 % inclusion affecting clarity visible from table area and less than 50 % of it is black
VM Less than 25 % inclusion affecting clarity visible from table area and less than 75 % of it is black
VH Less than 25 % inclusion affecting clarity visible from table area and more or less all are black
SN Less than 50 % inclusion affecting clarity visible from table area and none of its is black
SV Less than 50 % inclusion affecting clarity visible from table area of which less than 25 % are black
SS Less than 50 % inclusion affecting clarity visible from table area of which less than 50 % are black
SM Less than 50 % inclusion affecting clarity visible from table area of which less than 75 % are black
SH Less than 50 % inclusion affecting clarity visible from table area and more or less all are black
MN Less than 75 % inclusion affecting clarity visible from table area and none of its is black
MV Less than 75 % inclusion affecting clarity visible from table area of which less than 25 % are black
MS Less than 75 % inclusion affecting clarity visible from table area of which less than 50 % are blac
MM Less than 75 % inclusion affecting clarity visible from table area of which less than 75 % are black
MH Less than 75 % inclusion affecting clarity visible from table area and more or less all are black
HN The clarity is more or less based solely upon the table visible inclusions but none of it are black
HV The clarity is more or less based solely upon the table visible inclusions and less than 25% are black.
HS The clarity is more or less based solely upon the table visible inclusions and less than 50% are black.
HM The clarity is more or less based solely upon the table visible inclusions and less than 75% are black.
HH The clarity is more or less based solely upon the table visible inclusions and are mostly black.

For example, a black pin point in the table area for a VVS quality stone with no other inclusion visible from the stone the rating will be rated as HH because 100% inclusion is visible from the table area and is black, whereas an I2 stone with large pavilion gletz visible from crown will be rated as NN as table area is free of inclusions.

Black Inclusions are inclusions entrapped within a diamond and appear black in colour. This attribute indicates the magnitude/impact of black inclusion(s), affecting the overall clarity of the diamond, as compared to the total inclusions. These inclusions are generally referred to as 'Natts’. We at Royal Diam grade Black Inclusion as follows:

Image Grade Description
NN No black inclusion in the stone
VM Less than 20% of inclusions are black
MI more than 20% but less than 40% of the inclusion are black
MD more than 40% but less than 60% of the inclusion are black
HY more than 60% but less than 80% of the inclusion are black
VH more or less all the inclusions are black

For example even for a vvs quality stone with single pin point i.e. black in colour will be rated as Very heavy as 100 of the inclusion is black. On the other hand a heavily included I3 Stone with white gletz, crystal, and cloud will be graded as Nn or Vm depending upon the presence of black inclusion.

When an inclusion or a feather within a diamond is open near the surface, or if there is a chip, cavity, pit, nick or natural on the surface, then such flaws are graded as 'Opens'. Opens are chiefly the surface inclusion such as gletz, feather, etc that are open in nature as they float up to the surface of the stone. Under Royal Grading System we grade open as follows:

Grade Description
NN No open inclusion present in the Stone
VM Very minor opens in the stone
MI Minor opens in the stone
MD Medium opens in the stone
HY Heavy opens in the stone
VH Very Heavy opens in the stone

Further opens are located in three distinct parts of the stone i.e. Table, Crown and Pavillion. At every individual position open grading is categorized to allocate the nature of open in particular areas. For example Tnn, Cmd, Pvh indicates no open in table, medium open in crown and very high open in pavilion side.

These are naturally occurring lines, at times even clustered together indicating irregular growth of the diamond crystal during its formation. These line like structures usually transparent and invisible to the naked eye affect the clarity and hence the price of high clarity diamonds.

In the RGS we grade Internal graining in the given manner:

Grade Description
NN No internal graining present in the stone
VM Very minor internal graining in the stone
MI Minor internal graining in the stone
MD Medium internal graining in the stone
HY Heavy internal graining in the stone
VH Very Heavy internal graining in the stone

Further opens are located in three distinct parts of the stone i.e. Table, Crown and Pavillion. At every individual position open grading is categorized to allocate the nature of open in particular areas. For example Tnn, Cmd, Pvh indicates no open in table, medium open in crown and very high open in pavilion side.

This indicates two things; how densely the inclusions are located within the diamond, i.e whether they are concentrated or in a scattered pattern, and how visible it is from the naked eye. Under Royal Grading System we grade inclusion pattern as follows:

Image Grade Description
- NON No Inclusion present in the diamond
E0S1 Evenly scattered inclusion in the diamond but not visible from naked eye when looked from table
E1S1 Evenly scattered inclusion in the diamond and slightly visible from naked eye but cannot be distinguished when looked from table
- E2S1 Evenly scattered inclusion in the diamond and visible from naked eye but cannot be distinguished when looked from table
- E3S1 Evenly scattered inclusion in the diamond and clearly visible from naked eye from the table
E0S2 Semi scattered or kind of condensely scattered inclusions but not visible from naked eye when looked from table
E1S2 Semi scattered or kind of condensely scattered inclusions and slightly visible from naked eye but cannot be distinguished when looked from table
E2S2 Semi scattered or kind of condensely scattered inclusions and visible from naked eye but cannot be distinguished when looked from table
- E3S2 Semi scattered or kind of condensely scattered inclusions and clearly visible from naked eye from the table
E0C1 Light concentrated inclusion pattern but not visible from naked eye when looked from table
E1C1 Light concentrated inclusion pattern and slightly visible from naked eye but cannot be distinguished when looked from table
E2C1 Light concentrated inclusion pattern and visible from naked eye but cannot be distinguished when looked from table
- E3C1 Light concentrated inclusion pattern and clearly visible from naked eye from the table
E0C2 Semi concentrated inclusion pattern but not visible from naked eye when looked from table
E1C2 Semi concentrated inclusion pattern and slightly visible from naked eye but cannot be distinguished when looked from table
E2C2 Semi concentrated inclusion pattern and visible from naked eye but cannot be distinguished when looked from table
E3C2 Semi concentrated inclusion pattern and clearly visible from naked eye from the table
- E0C3 Heavily concentrated inclusions but not visible from naked eye when looked from table
E1C3 Heavily concentrated inclusions and slightly visible from naked eye but cannot be distinguished when looked from table
E2C3 Heavily concentrated inclusions and visible from naked eye but cannot be distinguished when looked from table
E3C3 Heavily concentrated inclusions and clearly visible from naked eye from the table

For example a vs quality stone with a single black inclusion will be termed as E3C3 type of stone or an I1 stone with a single large gletz will also be termed as E3C3.