The Scandinavian diamond nomenclature of 1969 (Scan.D.N.) for the first time differentiated between the terms
flawless and internally flawless
This built the first bridge between the two different methods of clarity grading. The clarity grading according to Scan.D.N. comprises internal and external blemishes of a cut diamond, with the exception of minimal external features in the first clarity grade.
In the new edition of 1980, there are five main grades, with 2, resp. 3 sub-divisions in the case of piques.
The main grades are called:
Loupe clean, VVS, VS, SI, P.
For clarity grading an achromatic and aplanatic
diamond loupe with a wide viewing field is prescribed. In order to save
time it is suggested that for the sub-grade "loupe clean" (flawless and
internally flawless) a 10 x magnification of a microscope be used.
Clarity grading according to Scan.D.N. may only be made on loose (unmounted) stones. This, however, does not apply to the P grades: a mounted stone exhibiting distinctly visible internal and/or external characteristics will in any case be placed in the P grade.
The basic tool of the grader is the diamond loupe. Scan.D.N. defines it as a triplet 10 x magnifying lens of high quality, corrected for chromatic and spheric aberration and with a field of visibility large enough to see an entire stone of 4 to 5 ct. The frame of the lens must be black or/and grey, white, or chrome colored.
The SCAN.D.N. Clarity Scale
The use of a microscope specially constructed for finding both internal and external characteristics facilitates the work and is timesaving. The sub grades FL and IF may be assessed only after examination with a diamond microscope.
The definition of the sub-grades can be described - in shortened form - as follows:
|Loupe clean||flawless (fl)
Cut diamond free from internal and external flaws are tested by an expert under a microscope with 10 x magnification.
Exceptions are: small naturals or extra facets, minor rough places on the girdle, in as far as they are not visible from the crown or flatten the girdle.
internally flawless (if)
Cut diamond absolutely free from internal faults tested by an expert under a microscope with 10 x magnification. External features should be so small that they can easily be removed by polishing with very little loss of weight.
For diamonds under half a carat (0.47 ct) the term "loupe clean" is used. Sub-division for brilliants above half a carat.
|VVS 1 + 2||VVS 1 (10 x loupe)
There must not be any inclusion in the field of the table. Very, very small inclusions are allowable in the rest of the stone. External faults must be minimal.
VVS 2 (10 x loupe)
Very, very small inclusions anywhere in the stone, only smallest external defects allowed.
|VS 1 + 2||VS 1 (10 x loupe)
Only the smallest inclusions are allowable in the field of the table, only small faults elsewhere in the stone. Small external faults.
VS 2 (10 x loupe)
Very small internal faults, also under the table. Small external defects.
|SI 1 + 2||SI 1 (10 x loupe)
Small internal faults, also under the table, if not too obvious, not visible with the naked eye. Some definite external features.
SI 2 (10 x loupe)
Small, easily discernable inclusions in the table, not visible with the naked eye. Some definite external features.
|P1 - 3||P 1 (10 x loupe and naked eye)
Inclusion easily recognizable with the loupe, but visible with difficulty with the naked eye through the crown, not influencing the brilliance. Definite external faults.
P 2 (10 x loupe and naked eye)
Large and numerous inclusions, just visible with the naked eye through the crown. Diminishing the brilliance. Definite external faults.
P 3 (naked eye)
Large and numerous inclusions, easily visible with the naked eye, diminishing the brilliance. Definite external faults.