DRAFT UGANDA STANDARD  
  DUS 2257  
First  Edition  
2020 -mm-dd 
 
 
 Reference number  
DUS 2257 : 2020 
© UNBS 2020   
  
Refined Gold  — Specification   
 DUS 2257 : 2020  
ii © UNBS 2020  – All rights reserved  
 Compliance with this standard does not, of itself confer immunity from legal obligations  
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct applicatio n 
© UNBS 2020   
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, including photocopying and microfilm, without prior written 
permission from UNB S. 
Requests for permission to reproduce this document should be addressed to  
The Executive Director  
Uganda National Bureau of Standards  
P.O. Box 6329  
Kampala  
Uganda  
Tel: +256 41 4 333 2 50/1/2/3  
Fax: +256 41 4 286 123  
E-mail: info@unbs.go.ug  
Web: www.unbs.go.ug  DUS 2257 :2020  
© UNBS 2020  – All rights reserved  iii 
 Contents  Page 
Foreword  ................................ ................................ ................................ ................................ ............................  iv 
1 Scope  ................................ ................................ ................................ ................................ ......................  1 
2 Normative references  ................................ ................................ ................................ ............................  1 
3 Terms and definitions  ................................ ................................ ................................ ...........................  1 
4 General Requirements  ................................ ................................ ................................ ..........................  1 
4.1 Grading and Fineness  ................................ ................................ ................................ ...........................  1 
Refined gold shall be characterised in terms of grade or fineness as described below;  ..........................  1 
4.2 Appearance  ................................ ................................ ................................ ................................ ............  2 
4.3 Dimensions  ................................ ................................ ................................ ................................ ............  2 
4.4 Weight  ................................ ................................ ................................ ................................ .....................  2 
4.5 Materials and Manufacture  ................................ ................................ ................................ ...................  2 
4.6 Specific requirements  ................................ ................................ ................................ ...........................  2 
5 Product Marking  ................................ ................................ ................................ ................................ .... 3 
6 Sampling  ................................ ................................ ................................ ................................ ................  3 
Annex  A (normative)  Test method for chemical analysis of refined gold by Cupellation Fire 
Assay  ................................ ................................ ................................ ................................ ......................  4 
A.1 Scope  ................................ ................................ ................................ ................................ ......................  4 
A.2 Summary of Test Method  ................................ ................................ ................................ .....................  4 
A.3 Interferences  ................................ ................................ ................................ ................................ ..........  4 
A.4 Apparatus  ................................ ................................ ................................ ................................ ...............  4 
A.5 Reagents and Materials  ................................ ................................ ................................ ........................  4 
A.6 Procedure  ................................ ................................ ................................ ................................ ...............  5 
A.7 Calcul ation  ................................ ................................ ................................ ................................ .............  6 
Bibliography  ................................ ................................ ................................ ................................ ........................  7 
 DUS 2257 : 2020  
iv © UNBS 2020  – All rights reserved  
 Foreword  
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry of Trade , Industry and 
Cooperatives established unde r Cap 327 , of the Laws of Uganda , as amended .  UNBS is mandated to co -
ordinate the elaboration of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex Alimentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT  Agreement  of the World Trade Organisation (WTO).  
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a give n field or area and consists of key stakeholders 
including government, academia, consumer groups, private sector and other interested parties.  
Draft Uganda Standards adopted by the Technical Committee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council.  
The committee responsible for this document is Technical Committee UNBS /TC 16, Petroleum , Subcommittee 
SC 2, Petroleum and Petroleum Products . 
 
 DRAFT UGANDA STANDARD  DUS 2257 : 2020  
 
© UNBS 2020  – All rights reserved  1 
 Refined Gold  — Specification   
1 Scope   
This Draft Uganda Standard specifies the requirements and methods of sampling and test for  refined gold in 
cast bar form . 
2 Normative references   
The following referenced documents 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 ref erenced document (including any amendments) applies.  
DUS 2258:2020  Test Method for Chemical Analysis of Refined Gold  by Direct Current Plasma Atomic 
Emission Spectrometry  
3 Terms and definitions   
For the purposes of this document, the following terms and d efinitions apply.  
3.1  
Fineness  
gold content measured in parts per thousand; example; ( a fineness of 999.9 equals 99.99 per cent gold.  
ISO and IEC maintain terminological databases for use in standardization at the following addresses:  
— ISO Online brows ing platform: available at http://www.iso.org/obp  
4 General Requirements  
4.1 Grading  and Fineness  
 Refined gold shall be characterised in terms of grade or fineness as described below;  
a) Grade 99.5 —Gold having a minimum fineness of 995.  
b) Grade 99.95 —Gold havi ng a minimum fineness of 999.5.  
c) Grade 99.99 —Gold having a minimum fineness of 999.9.  
d) Grade 99.995 —Gold having a minimum fineness of 999.95.  
Note: The minimum acceptable fineness is 995.0 parts per thousand fine gold   
2 © UNBS 2020  – All rights reserved  
 4.2 Appearance  
The surface of the bar sh all be smooth, free of any irregularities such as layering, surface cavities, bubbles, 
spots, blowholes or shrinkage  
4.3 Dimensions  
All shapes and sizes of the fine kilobar may have minor variations, the following measurements should be 
considered as the b enchmarks  
a) Maximum Length: 119mm  
b) Maximum Width: 55mm  
c) Maximum Thickness: 9mm  
4.4 Weight  
For 1 Kilogram of tradable gold bar meeting the requirements of this standards shall have a minimum of 995 
purity and / or minimum of 999.9 purity per thousand parts of g old 
For small tradable gold bar an exact weight of 1.00g, 2.5g, 5.00g, 10.00g, 50.00g, 100.00g, 10 tola with a 
weight of 11.6638g  shall have  minimum 999.0 purity and / or higher purity of 999.9 per thousand parts of fine 
gold 
4.5 Materials and Manufacture  
The metal may be produced by any process that yields a product capable of meeting the requirements of this 
specification.  
The purchaser or regulatory authority , upon request, shall be informed of the refining process used  
4.6 Specific requirements  
Refined gold shall comply with the limits specified in Table 1, when tested in accordance with DUS 2258  
Table 1 — Specific requirements for Refined Gold  
ElementA Composition,%  
Grade 99.5B Grade 99.95  Grade 99.99  Grade 99.995  
Gold, (min)  99.5 - - - 
Gold, (min) (by difference)  - 99.95  99.99  99.995  
Silver + copper, (max)  - - 0.04 - 
Silver, (max)   - 0.035  0.009  0.001  
Copper, (max)  - 0.02 0.005  0.001  
Palladium, (max)   - 0.02 0.005  0.001  
Iron, (max)  - 0.005  0.002  0.001  
Lead,(max)  - 0.005  0.002  0.001  
Silicon, (max)   - - 0.005  0.001  
Magnesium, (max)  - - 0.003  0.001  
Arsenic, (max)  - - 0.003  - DUS 2257 : 2020  
© UNBS 2020  – All rights reserved  3 
 Bismuth, (max)  - - 0.002  0.001  
Tin,( max)  - - 0.001  0.001  
Chromium, (max)  - - 0.0003  0.0003  
Nickel, (max)  - - 0.0003  - 
Manganese, (max)  - - - 0.0003  
A By agreeme nt between manufacturer and purchaser analyses may be required and limits established for elements not specified in this tabl e. 
B  Chemical composition of materials required for Grade 99.5 refined gold shall be determined by a test method similar to the fi re assay te st method listed 
in the Annex  A 
 
5 Product Marking  
Gold bars shall bare the following information  in legible and indelible marking ; 
a) Serial Numbers  
b) Hallmark/brand stamp of the refiner  
c) Fineness (to four significant figures)  
d) Weight (expressed in g rams, kilograms or troy ounces)  
e) Year of manufacture, or if not, the year must be stated on the accompanying certificate of the 
manufacturer  
6 Sampling  
A sample may be taken from the melt before pouring  (A single melt or bar(s) cast from a single melt shall  
constitute a lot for sampling.)  
The amount of sample taken shall be in accordance to that specified in DUS 2258  
  
4 © UNBS 2020  – All rights reserved  
 Annex  A 
(normative)  
 
Test method for chemical analysis of refined gold by Cupellation  Fire 
Assay  
A.1 Scope  
This test method covers the cupell ation analysis of Grade 99.5 refined gold for gold content  
A.2 Summary of Test Method  
The weighed sample along with required silver, copper, and lead is cupelled until all base metal is absorbed 
and only the precious metals remain. The silver is then remov ed by dissolution with nitric acid. The remaining 
gold is dried, annealed, and weighed. Synthetic proof samples of known amounts of gold are also assayed 
and the sample is corrected for gains or losses in the proof sample.  
A.3 Interferences  
The presence of  the following elemental concentrations will lead to erroneous results.  
Element  Max %  
Nickel, Iron, Tin  2.0 
Tungsten  0.5 
Palladium, Platinum  00.1 
Iridium, Rhodium, Ruthenium, Osmium  0.01 
 
A.4 Apparatus  
 Muffle furnace, capable of maintaining 1250°C an d having adjustable air flow control.  
 Analytical balance, capable of weighing 60.002 mg.  
 Rolling mill.  
 Platinum baske t. 
A.5 Reagents and Materials  
 Nitric acid, 22 ° Baume´, 1.169 6 0.01 specific gravity by hydrometer.  
 Nitric acid, 32° Baume´, 1.285 6 0.01 s pecific  gravity by hydrometer.  
 Lead foil.  
 Silver wire, 99.99 % (<0.001 ppt Au).  DUS 2257 : 2020  
© UNBS 2020  – All rights reserved  5 
  Copper disks, 25 mg.  
 Proof gold wire, 99.999 %.  
A.6 Procedure  
Sample Preparation —Wire brush chill pin samples to remove glass particles from surface, then cut and roll. 
After r olling, inspect the sample for inclusions or other signs of segregation. Drillings and grain samples are as 
is. 
Weigh s amples in triplicate at 0.50 g and place in 2.5 g lead cornucopias, along with 1.25 g of fine silver and 
1/2 disk of copper . 
Prepare two pr oofs per sample. Weigh fine gold at 0.4975 +/ - 0.00050 g. Add silver at 1.25 g, along with 1/2 
disk of copper.  
Close lead cornucopias and compress with pliers into spheres to fit cupels. Place in numbered tray 
compartments.  
Load a set of 15 (three rows of five) 1 in. magnesite cupels into the muffle furnace (no air flow) at 
approximately 1225°C and allow to dry for 30 min. calibrate  the temperature of the furnace by noting the 
temperature necessary to melt pure gold.  
Carefully place each lead wrapped sample  in a cupel, starting with the next to the front row, as follows:  
B B B B B 
3A P 3B P 3C 
2A P 2B P 2C 
1A P 1B P 1C 
B B B B B 
where:  
B = blank cupel, and  
P = proof.  
Close the door and wait 2 to  3 min until all samples become molten. Open the draft and adjust after 1 min for 
sufficient draft  (fumes visibly rising off cupels and flowing back to vent in rear  of furnace).  
Close the door and wait 2 to 3 min until all samples become molten. Open the draft and adjust after 1 min for 
sufficient draft (fumes vis ibly rising off cupels and flowing back to vent in rear of furnace).  
After 8 to 10 min the samples will appear silvery but not solidified. At this point remove the cupels from the 
furnace one at a time and place in front of the furnace door, where the samp les will immediately solidify and 
blink.  
Once cooled, remove beads from cupels with flat pliers and place in dimpled porcelain trays.  
Clean beads by squeezing bead with flat plier and brushing away adhering bone ash.  
Flatten beads with one middle blow and several end blows. Roll beads to about 0.040 in. by passing twice 
through hand roller, and anneal at 1550°F (843.3°C) for 7 min.  
Roll beads to a thickness of 0.015 in. by passing twice through hand roller, and anneal again at 1550°F 
(843.3°C) for 7 min. Fi nally roll beads to 0.012 in., and anneal one final time at 1550°F (843.3°C) for 7 min. 
The edges of the rolled bead must be smooth and have no roughness. It is important that all fillets of each row 
are the same size and thickness.   
6 © UNBS 2020  – All rights reserved  
 Coil fillets into “coro nets” or spirals using thin -nose pliers or rolling tool.  
Place coronets in a platinum basket in a definite pattern so as not to mix each coronet.  
Place the basket in 22° Baume´ nitric acid at 105°C (boil gently) for 45 min, for full basket.  
Remove the bask et, rinse with hot deionized water and place in 32° Baume´ nitric acid at 110°C (boil gently) 
for 45 min, for full basket.  
Rinse the basket first in hot deionized water, then a hot 5 % ammonium hydroxide solution rinse, and three 
more hot deionized water r inses.  
Place the basket (still containing coronets) on the hot plate and dry.  
Place the basket in an annealing furnace at 1550°F (843.3°C) for 7 min.  
Cool gold coronets and weigh  
A.7 Calculation  
Gold Concentration : 
Gold concentration in parts per thousand5  = (A x B x 1000)/C  
where:  
A = Final gold weight, g,  
B = Average of two proof factors, and  
Proof factor5  = Initial proof gold weight, g  / Final proof gold weight, g  
C = Initial sample weight, g.  DUS 2257 : 2020  
© UNBS 2020  – All rights reserved  7 
 Bibliography  
[1] ASTM B562 Standard Specification for Refined  Gold  
[2] GDL Gold Bar Specifications  
[3] LBMA  Gold Bar Specifications  
 DUS 2257 : 2020  
© UNBS 2020  – All rights reserved  9 
 Certification marking  
Products that conform to Uganda standards may be marked with Uganda National Bureau of Standards 
(UNBS) Certification Mark shown in the figure below.  
The use of  the UNBS Certification Mark is governed by the Standards Act, and the Regulations made 
thereunder. This mark can be used only by those licensed under the certification mark scheme operated by 
the Uganda National Bureau of Standards and in conjunction with  the relevant Uganda Standard. The 
presence of this mark on a product or in relation to a product is an assurance that the goods comply with the 
requirements of that standard under a system of supervision, control and testing in accordance with the 
certifi cation mark scheme of the Uganda National Bureau of Standards. UNBS marked products are 
continually checked by UNBS for conformity to that standard.  
Further particulars of the terms and conditions of licensing may be obtained from the Director, Uganda 
National Bureau of Standards.  
 
 DUS 2257 : 2020    
 
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