ISO 6893:2024

International
Standard
ISO 6893
First edition
Jewellery and precious metals —
2024-04
Inspection of batches of small
diamonds — Terminology,
classification and test methods
Joaillerie, bijouterie et métaux précieux — Contrôle des lots
de petits diamants — Terminologie, classification et méthodes
d’examen
Reference number
© ISO 2024
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ii
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 General . 3
4.1 Batch specifications and characteristics .3
4.2 Inspection .3
5 Authentication . 4
6 Sieving . 4
6.1 General .4
6.2 Estimating the total mass of a small diamond batch by sieving and counting .4
6.3 Estimating a batch size by sieving and weighing .4
6.4 Sieving small diamonds .4
6.4.1 Method . .4
6.4.2 Using sieving plates in a correct order .5
6.4.3 Maximum size of a sieved batch .5
6.4.4 Preventing damages of sieved diamonds .5
6.4.5 Regular control of sieve plates accuracy .6
7 Mass of a batch . 6
7.1 Testing .6
7.2 Expression of the weighed mass of a batch .6
8 Measurements . 6
8.1 Measuring small diamonds .6
8.2 Traditional measurements of single small diamonds .6
8.3 Measuring a small diamond with a profile projector .6
8.4 Measuring automatically dimensions of small diamonds in batch .7
8.5 Description of dimension for a batch . .7
9 Batch size . 7
9.1 Testing .7
9.2 Estimation .7
9.2.1 Estimation by sampling . .7
9.2.2 Estimation using mass and diameter.8
9.3 Description .8
10 Sampling . 8
10.1 Inspecting a batch by sampling .8
10.1.1 General conditions .8
10.1.2 Drawing diamond samples from a batch .8
10.2 Sampling plans for the inspection of a batch of small diamonds .9
10.3 Inspection plan and multiple criteria .9
11 Cut . 9
11.1 Description of cut in a homogenous batch .9
11.2 Description of cut in an inhomogenous batch .9
11.3 Shape .9
11.4 Proportions.9
11.4.1 Testing the proportions of small diamonds .9
11.4.2 Description of proportion grades .10
11.5 Polish .10
11.5.1 Testing the polish of small diamonds .10
11.5.2 Polish grades .10

iii
11.6 Symmetry .11
11.6.1 Testing the symmetry of small diamonds .11
11.6.2 Symmetry grades .11
12 Colour .11
12.1 Testing the colour of small diamonds .11
12.2 Colour grades .11
13 Fluorescence .12
13.1 Testing the fluorescence of small diamonds . 12
13.1.1 Testing the fluorescence by visual means . 12
13.1.2 Testing the fluorescence by spectrometry. 13
13.2 Description of the fluorescence . 13
14 Clarity .13
14.1 Testing the clarity of small diamonds . 13
14.2 Clarity grades . 13
15 Content of a test report . 14
Annex A (informative) Corresponding figures for round brilliant cut .16
Annex B (informative) Flowchart for «sampling control» .18
Bibliography .21

iv
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
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This document was prepared by Technical Committee ISO/TC 174, Jewellery and precious metals.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
Introduction
ISO 24016 describes the terminology, the classification and test methods that apply for the grading of
polished diamonds over 0,25 ct (carat). This category is commonly named “large diamonds” as opposed to
the category of “small diamonds”.
From an economic perspective, on the jewellery and watchmaking industries, the low price of each single
small diamond – compared to that of a large diamond - is widely compensated by the enormous quantity of
small diamonds used.
As for a large diamond, the quality of a small diamond is mainly defined by its carat mass, its colour, its
clarity and its cut. But, specifically the inspection of small diamonds faces one main challenge. They are sold
by batches, sometimes as large as 10 000 units. When these batches are homogeneous, an inspection per
sampling is possible.
This document is proposed to companies involved in the small diamond trade and willing, in the frame of
their commercial relationship, to agree on both a defined quality and its inspection methodology.
It is agreed by both parties that the batches that are supplied for inspection by sampling are on a level
of the supply chain that provides the necessary homogeneity. Small diamonds are already controlled in
different countries and today there is a need for harmonizing the technical principles of inspection of small
diamonds. This harmonization will benefit the jewellery and watchmaking industries in large, because their
reputations are inextricably linked to a stringent compliance with their product quality specifications.
This document aims to clarify and ease the relationship between diamantaires and companies decorating
their products with small diamonds, which consequently strengthens the end consumer confidence in the
jewellery, watchmaking and all other luxury industries.
This document completes ISO 18323 and ISO 24016.

vi
International Standard ISO 6893:2024(en)
Jewellery and precious metals — Inspection of batches of small
diamonds — Terminology, classification and test methods
1 Scope
This document specifies the terminology, classification and test methods that are used for the inspection
of batches of unmounted polished colourless diamonds with single mass smaller than or equal to 0,25 ct
(carat).
While the inspection of a batch is made one diamond at a time, the use of this document is not to be claimed
for one single diamond only nor for fancy coloured diamonds, nor for synthetic diamonds, nor for treated
diamonds, neither for assembled stones.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 2859-1:1999, Sampling procedures for inspection by attributes — Part 1: Sampling schemes indexed by
acceptance quality limit (AQL) for lot-by-lot inspection
ISO 18323, Jewellery — Consumer confidence in the diamond industry
ISO 24016, Jewellery and precious metals — Grading polished diamonds — Terminology, classification and
test methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18323, ISO 24016 and the
following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
diamond
mineral consisting essentially of carbon crystallised in the isometric (cubic) crystal system, with a hardness
on the Mohs’ scale of 10, a specific gravity of approximately 3,52 and a refractive index of approximately
2,42, created by nature
Note 1 to entry: The denomination “diamond” without further specification always implies “natural diamond”. These
two terms are equivalent and carry the same meaning.
[SOURCE: ISO 24016:2020, 3.1.1]
3.2
small diamonds
diamonds (3.1) of individual mass smaller than or equal to 0,25 ct

3.3
batch
series of small diamonds (3.2) conforming to the batch specification (3.4)
3.4
batch specification
written or verbal description of a batch (3.3) of small diamonds (3.2) comprising authenticity, cut (3.6),
batch size (3.5), and/or dimension, and/or colour grade, and/or clarity grade, and/or cut grade (3.12) and/or
proportion grade (3.11) and/or symmetry grade (3.9), and/or polish grade (3.8)
3.5
batch size
quantity of small diamonds (3.2) in a batch (3.3)
3.6
cut
shape, proportions, polish and symmetry of a diamond (3.1)
Note 1 to entry: The term finish encompasses polish and symmetry.
[SOURCE: ISO 24016:2020, 3.5]
3.7
cutting style
facets arrangement of a polished diamond (3.1)
EXAMPLE brilliant, step cut
3.8
polish grade
grade taking into consideration the surface condition of a diamond (3.1)
3.9
symmetry grade
grade taking into consideration the exactness of the shape of a diamond (3.1), the arrangement of its facets
and in some circumstances its girdle regularity
3.10
finish grade
grade combining the symmetry grade (3.9) and the polish grade (3.8)
3.11
proportion grade
grade combining table size, crown height and/or crown angle, pavilion depth and/or pavilion angle, star
length, pavilion half facet length, girdle thickness, total depth and in some circumstances culet size
3.12
cut grade
grade combining the proportion grade (3.11) and the finish grade (3.10)
3.13
inspection
examination of the specifications of small diamonds (3.2) and determination of its conformity with detailed
requirements or, on the basis of professional judgement, with general requirements
Note 1 to entry: Examination can include direct or indirect observations, which can include measurements or the
output of instruments.
[SOURCE: ISO 17000:2020, 6.3, modified — The original text “an object of conformity assessment” has been
replaced by “the specifications of small diamonds”, Note 2 and Note 3 to entry have been removed]

3.14
sieving
process of separating round small diamonds (3.2) according to their diameter, by means of one or more sieves
[SOURCE: ISO 2395:1990, 3.3.1, modified — the original text “a mixture of particules” is replaced by “round
small diamonds” and the original word “size” is replaced by “diameter”, note 1 has been removed.]
4 General
4.1 Batch specifications and characteristics
Single diamonds shall be tested only as part of a batch.
For keeping a consistent quality management on a long-term basis, after its clear definition, the same
specification for the same characteristics should be maintained as long as possible.
At least the following characteristics shall specify a batch of small diamonds:
— the total carat mass;
— dimension class/sieve number;
— colour grade;
— clarity grade;
— cutting style;
— shape.
The following characteristics may be specified:
— batch size;
— finish grade;
— proportion grade;
— cut grade;
— crown height;
— girdle thickness;
— nature of the girdle;
— degree of fluorescence;
— tightened dimensions tolerance for roundness, for maximum total depth or any other customized
dimensions tolerance.
4.2 Inspection
To ensure impartiality during inspection, the inspection plan that applies to the inspected batch shall not be
communicated to the inspector.
For the inspection of a batch by sampling, the inspector shall know the sample size to apply.
NOTE Figure B.1 shows a flowchart which describes the preparation of a batch for sampling.

Batch size: 200
Code letter: G (General inspection level II)
Sample size: 32
When multiple criteria (e.g. colour and clarity) are inspected, one diamond that would be defective for
several criteria is only counted once as a defective diamond only if the inspector considers that the defective
criteria are linked together (e.g. a very bad clarity grade affects the colour). This case is also considered in
ISO 2859-1:1999, 4.1.
EXAMPLE 1 Assuming that a batch contains one diamond with a colour grade J and a clarity grade P2, the inspector
can count the defective diamond only once because he considers that presence of numerous large inclusions is linked
to the J colour grade.
EXAMPLE 2 Assuming that a batch contains one diamond with a colour grade J and a clarity VVS, the inspector can
count the defective diamond twice because he can consider that the clarity grade is not linked to the colour grade.
5 Authentication
The nomenclature used for describing the authenticity of a diamond batch shall conform to the rules
specified in ISO 18323.
Prior to any inspection, the authentication of all diamonds in a batch shall be ensured by appropriate
diamond verification means.
The method and devices that were used for authenticating a diamond batch shall always be available.
Non-destructive methods for authenticating small diamonds may include and are not limited
...