ISO/FDIS 11211-2
(Main)Grading polished diamonds — Part 2: Test methods
Grading polished diamonds — Part 2: Test methods
ISO 11211-2:2002 specifies methods for the grading of natural unmounted polished diamonds within the D to Z series and the grading criteria, other than for the colour of naturally coloured diamonds.
Diamants taillés — Partie 2: Méthodes d'essai
General Information
Relations
Standards Content (Sample)
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 11211-2
ISO/TC 174
Grading polished diamonds —
Secretariat: DIN
Part 2:
Voting begins on:
2002-05-09
Test methods
Voting terminates on:
Diamants taillés —
2002-07-09
Partie 2: Méthodes d'essai
Please see the administrative notes on page iii
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ISO/FDIS 11211-2:2002(E)
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ISO 2002
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ISO/FDIS 11211-2:2002(E)
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ii © ISO 2002 – All rights reserved
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ISO/FDIS 11211-2:2002(E)
In accordance with the provisions of Council Resolution 15/1993, this document is circulated in the English
language only.
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ISO/FDIS 11211-2:2002(E)
Contents Page
Foreword.vi
1 Scope.1
2 Normative reference.1
3 Terms and definitions .1
4 Identification.1
5 Weight and measurements .2
5.1 Weight.2
5.2 Measurements.2
6 Colour and fluorescence.2
6.1 Cleaning of masterstones.2
6.2 Masterstones for colour.2
6.3 Procedure.2
6.3.1 Precautions.2
6.3.2 Cleaning.3
6.3.3 Comparisons.3
6.3.4 Round stones.3
6.3.5 Fancy shapes.3
6.3.6 Colours.3
6.3.7 Lighting.3
6.3.8 Positioning.3
6.3.9 The grade.3
6.3.10 Master-eye effect.5
6.4 Description of fluorescence .7
6.4.1 Equipment and references.7
6.4.2 Masterstones for fluorescence.7
6.4.3 Working conditions and methodology .7
6.4.4 Fluorescence, other than blue.7
7 Clarity.7
7.1 General.7
7.2 Apparatus.7
7.3 Procedure.8
7.3.1 General.8
7.3.2 Lighting.8
7.3.3 Distance.8
7.3.4 Plotting.8
7.3.5 Plotting symbols.10
7.3.6 Laser drill holes .11
7.3.7 Surface grain lines.11
7.3.8 Internal graining.11
7.3.9 General.11
7.3.10 Clarity examples.12
8 Shape.34
9 Proportions.34
9.1 Appropriate instruments.34
9.2 Description.34
9.2.1 Table sizes.34
9.2.2 Crown height.34
9.2.3 Pavilion depth.34
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ISO/FDIS 11211-2:2002(E)
9.2.4 Girdle thickness.34
9.2.5 Culet size.34
9.3 Comments on proportions.34
10 Finish (grading of symmetry and polish).35
10.1 Symmetry.35
10.2 Polish.38
11 Expression of results.38
12 Comments.38
13 Test report.39
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ISO/FDIS 11211-2:2002(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technical
committees. Each member body interested in a subject for which a technical committee has been established has
the right to be represented on that committee. International organizations, governmental and non-governmental, in
liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical
Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3.
The main task of technical committees is to prepare International Standards. Draft International Standards adopted
by the technical committees are circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this part of ISO 11211 may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 11211-2 was prepared by Technical Committee ISO/TC 174, Jewellery.
ISO 11211 consists of the following parts, under the general title Grading polished diamonds — Part 2: Test
methods:
— Part 1: Terminology and classification
— Part 2: Test methods
Part 3 of ISO 11211, dealing with the colour of naturally coloured diamonds, is in the course of preparation.
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FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 11211-2:2002(E)
Grading polished diamonds —
Part 2:
Test methods
1 Scope
This International Standard specifies methods for the grading of natural unmounted polished diamonds within the D
to Z series and the grading criteria, other than for the colour of naturally coloured diamonds.
2 Normative reference
The following normative document contains provisions which, through reference in this text, constitute provisions of
this part of ISO 11211. For dated references, subsequent amendments to, or revisions of, any of these publications
do not apply. However, parties to agreements based on this part of ISO 11211 are encouraged to investigate the
possibility of applying the most recent edition of the normative document indicated below. For undated references,
the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of
currently valid International Standards.
ISO 11211-1:2002, Grading polished diamonds — Part 1: Terminology and classification
3 Terms and definitions
For the purposes of this part of ISO 11211, the terms and definitions given in ISO 11211-1 and the following apply.
3.1
first generation masterstone
diamond that has been selected by direct comparison with the relevant masterstone in the set of masterstones
originally used to establish the D to Z grades for the International Organization for Standardization, as specified in
7.1.1 of ISO 11211-1:2002 and equal in hue, tone and saturation to the relevant original masterstone
3.2
second generation masterstone
diamond that has been selected by direct comparison with the relevant first generation masterstone (3.1) and equal
in hue, tone and saturation to the relevant first generation masterstone
4 Identification
It shall be the responsibility of the examiner to establish that the stone under examination is a diamond before it is
graded in accordance with 3.1 of ISO 11211-1:2002, and be aware of the possibilities of the stone being a synthetic
diamond, a treated diamond or an assembled stone.
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ISO/FDIS 11211-2:2002(E)
5 Weight and measurements
5.1 Weight
Maintain all balances used to establish the carat weight of diamonds to ensure accuracy. Prior to weighing, all
diamonds shall be clean.
5.2 Measurements
Use instruments accurate in millimetres to two decimal places to measure the dimensions of a diamond.
Measurement parameters are specified in 6.2 of ISO 11211-1:2002. For round stones, determine minimum and
maximum diameters by making at least four measurements at differing points on the diameter of the diamond.
Clearly establish minimum and maximum diameter measurements.
For stones other than rounds, determine minimum and maximum diameters by making two measurements (or more
if applicable) across the apparent length and width of the diamond. Clearly establish the length and width plus any
other descriptive measurements.
For determining depth (total height), make measurements perpendicular to the table facet and record the
established maximum figure on the report.
6 Colour and fluorescence
6.1 Cleaning of masterstones
Prior to grading, clean each masterstone with an organic solvent. Masterstones with dirty girdles and encrusted
diamonds shall be cleaned by appropriate means (e.g. by boiling in an acid).
Keep the masterstones clean.
6.2 Masterstones for colour
Use only round, brilliant-cut diamonds for this purpose.
First generation masterstones shall be not smaller than 0,60 ct. Second generation masterstones shall be not
smaller than 0,30 ct. Masterstones shall not have internal characteristics that are eye visible under normal or
corrected-to-normal vision, or otherwise affect colour or decrease the transparency when viewed through the
pavilion. The fluorescence shall be not greater than the grade “Faint”. Finish shall be at least “Good”. Proportions
shall be in the “A range”. All stones in a set shall be of similar weight and proportions, and the nature of the girdles
shall be the same.
Masterstones shall be of the “yellow series” and shall be positioned either at the higher limit or the lower limit for
each grade (with the exception of the “D” grade where there cannot be a masterstone positioned at the higher limit).
All masterstones in any one set shall be positioned either at the higher or the lower limit for each grade.
The second generation of masterstones shall be the last generation that shall be used by laboratories for the
issuing of test reports.
Masterstones should be positioned at the lower limit (maximum saturation) for each grade.
6.3 Procedure
6.3.1 Precautions
Do not grade for colour immediately following grading for fluorescence.
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ISO/FDIS 11211-2:2002(E)
Persons colour grading diamonds shall be aware of the “tiring factor” and limit the time spent grading according to
their individual capabilities.
6.3.2 Cleaning
Prior to grading, clean each submitted diamond with an organic solvent. Diamonds with dirty girdles and encrusted
diamonds shall be cleaned by appropriate means (e.g. by boiling in an acid).
6.3.3 Comparisons
The colour of the diamond to be graded shall be determined by visual comparison with masterstones and shall be
observed from the pavilion side between being almost parallel to the level of the girdle to being perpendicular with
the pavilion facets (see Figure 1). Place the stone between two of the masterstones and move the stone until the
correct position is found. Only view the diamond through the crown side to determine if it is a “coloured diamond”
(see ISO 11211-3, in preparation).
6.3.4 Round stones
Round stones shall be examined in several directions within the rotation axis indicated in Figure 1. If different
colours are observed, the predominant D to Z grade shall be conclusive.
6.3.5 Fancy shapes
The colour of fancy-shaped diamonds shall be graded in the directions indicated in Figure 2. In the case of cuts
with points or corners, these directions shall not be taken into account. If different colours are observed, the
predominant D to Z grade shall be conclusive.
6.3.6 Colours
Colours such as brown, brownish-yellow, grey, greyish-yellow (in the D-Z grades) shall be graded as if they were
within the same colour series as the masterstones. However, for grades M and below, such stones shall also be
evaluated in the face-up position for the description indicating the presence of these hues (see also ISO 11211-3,
in preparation).
6.3.7 Lighting
Colour grading shall be carried out under an artificial light source with a stable light output and simulating illuminant
D − D , in a light intensity of approximately 2 200 lx.
55 65
NOTE A convenient artificial light source is a commercial tubular fluorescent lamp with colour temperature of 5 500 K to
6 500 K.
The masterstones and the stone to be graded shall be placed with the table down on a dull white background
under the central area of the tube. Reflections and distractions from the environment shall be excluded.
Prevent direct view of the light sources.
6.3.8 Positioning
The diamond being graded and the masterstones shall be placed directly below the light source. For an observer
with normal eyesight, the distance between the light source and the diamond being graded shall be approximately
20 cm and the light intensity at that point shall be approximately 2 200 lx (see Figure 1).
6.3.9 The grade
The colour grade shall be given with one full colour grade or colour corresponding term in accordance with 7.1.1
and 7.2 of ISO 11211-1:2002. Combined grades shall be used in accordance with Table 1 of ISO 11211-1:2002.
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ISO/FDIS 11211-2:2002(E)
Key
1 Colour comparison
2 Naked eye
3 Light source
a
Viewing angle
b
Rotation axis
Figure 1 — Colour grading criteria
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ISO/FDIS 11211-2:2002(E)
Figure 2 — Examples of colour grading directions and directions in which colour grading shall not be
made for fancy-cut diamonds within the D-Z range
6.3.10 Master-eye effect
When comparing diamonds with a masterstone, the master-eye effect can occur (see Figure 3).
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ISO/FDIS 11211-2:2002(E)
a) The stone appears darker on the left side of the master and appears equally lighter on the right,
the stone is graded the same colour as the masterstone.
b) The stone appears darker on the left and the same as the masterstone on the right,
the stone is graded darker than the masterstone.
c) The stone appears to be the same on the left side of the masterstone and lighter on the right,
the stone is graded lighter than the masterstone.
Figure 3 — Master-eye effect
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ISO/FDIS 11211-2:2002(E)
6.4 Description of fluorescence
6.4.1 Equipment and references
The fluorescence description of a diamond shall be recorded when the stone is observed under a long-wave UV
lamp (approximately 365 nm) that has an output of 4 W to 8 W.
The description shall be made by comparison with a series of masterstones that characterize the intensities “none”
or “nil”, “faint” or “slight”, “medium” and “strong” in accordance with 7.4 of ISO 11211-1.
Three masterstones shall be required to achieve the correct fluorescence description for each diamond (see 6.4.2).
The masterstones and the stone under examination shall be positioned on a matt black background.
6.4.2 Masterstones for fluorescence
The masterstones shall be positioned at the maximum intensity of fluorescence for the intensities, “none”, “faint”,
and “medium”, and have a blue type fluorescence. The weight of each masterstone shall be a minimum of 0,25 ct,
and the shape shall be round.
6.4.3 Working conditions and methodology
The lighting conditions in the room used for comparing the fluorescence of a diamond against the fluorescence
masterstones shall not have an effect upon the stone under examination or the masterstones. The stone under
examination and the masterstones shall be positioned at a distance of approximately 10 cm from the UV source
and examined from the pavilion side from being almost parallel to the level of the girdle to perpendicular with the
pavilion facets, and an overall impression is gained.
6.4.4 Fluorescence, other than blue
If the hue of the fluorescence is other than blue, the intensity shall be considered in relation to the masterstones.
NOTE The hue may also be registered.
7 Clarity
7.1 General
Clarity grading shall be determined in accordance with the example diagrams in 7.3.10, as well as with clause 8 of
ISO 11211-1:2002. The practical grading for clarity shall be made with the greatest caution and shall not be made
under time pressure. Experience and regular practice shall be required to achieve accurate and consistent results.
Before it is graded, the stone shall be properly cleaned (6.3.2). A thorough examination through and on each of the
diamond's numerous facets, and along the entire girdle, shall be carried out.
7.2 Apparatus
The basic tool for clarity grading shall be the diamond loupe in accordance with clause 3.15 of ISO 11211-1:2002.
A microscope may be used to “find” internal and external characteristics, but only those characteristics seen with
the diamond loupe shall determine the grade.
NOTE The use of tweezers is suggested for holding a diamond
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ISO/FDIS 11211-2:2002(E)
7.3 Procedure
7.3.1 General
To determine the clarity grade of a diamond, no factors other than visibility shall be taken into account.
NOTE Generally, inclusions observed through the crown of a diamond have a greater effect upon the clarity grade than
those seen through the pavilion only.
7.3.2 Lighting
Clarity grading shall always be carried out under an artificial light source with a stable light output.
The light intensity at a distance of 20 cm shall be approximately 2 200 lx (see Figure 4).
NOTE A convenient artificial light source is a commercial tubular fluorescent lamp with corrected colour temperature of
5 500 K to 6 500 K.
7.3.3 Distance
A diamond being graded shall be held under the lamp at a distance of between 5 cm and 10 cm. Reflections and
distractions from the environment shall be excluded. To determine the visibility of internal and external
characteristics with the naked eye, the diamond shall be held at a distance from the lamp of approximately 30 cm,
in a position that allows light to enter through the crown, and only minimally through the pavilion (see Figure 4).
7.3.4 Plotting
Plot clarity grading characteristics on a diagram that describes the crown and pavilion facet arrangement of the
diamond being graded. Common shapes of various diamond cuts are specified in 9.2 of ISO 11211-1:2002. The
plot diagram on the report shall generally reflect the outline of the diamond combined with the facet distribution,
without necessarily reflecting the ratios of length and width.
Place the diagram on the report with the crown and pavilion views orientated so that an identical point on the girdle
of the two is positioned where they are closest to each other.
NOTE The purpose of plotting clarity characteristics on a report is only to describe the concluded grade.
Plot internal and external characteristics placed on the report diagram as accurately as possible in terms of size,
position and nature.
Plot internal characteristics in red. Plot external characteristics in green. Plot characteristics found to be in the
crown and/or girdle portions of the diamond on the crown diagram, and those in the pavilion portion on the pavilion
diagram. Plot any characteristics visible through the crown to the naked eye on the crown diagram. If a feather cuts
the pavilion, then it shall be plotted on the pavilion even if it is visible with the naked eye from the crown.
Plot reflecting or mirrored internal characteristics in their actual position only.
Accurately record on worksheets all internal and external characteristics, in terms of position, size and nature.
Plot external characteristics that affect the symmetry grade on the report using the same plot diagram as that used
to plot the clarity characteristics, or mention them in the comments section.
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ISO/FDIS 11211-2:2002(E)
Key
1 Naked eye
2 Loupe
3 Light source
4 Clarity
5 Clarity transparency
Figure 4 — Clarity grading criteria
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ISO/FDIS 11211-2:2002(E)
7.3.5 Plotting symbols
Use the following plotting symbols to record internal and external characteristics on reports and worksheets.
Table 1 — Internal characteristics Table 2 — External characteristics
a b c d a b c d
1C , 2P 1P , 2C 1C , 2P 1P , 2C
Key Key
Plot in red Plot in red Plot in green Plot in green
pinpoint inclusion bruting line
group of pinpoints pit or cavity
crystal inclusion scratch
dark in
...
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