Instruction and testing Procedure of Gold For Indian Hallmarking centre

Instruction and testing Procedure of Gold For Indian Hallmarking centre

or Simple operating procedure 

INSTRUCTIONS FOR RECEPTION AND DELIVERY

•         Start the balance in the morning and allow it time for warm-up, and check it.

•      Welcome the customers. Provide customer with necessary comfort and courtesy.

•       Brief the customer about BIS guidelines for accepting jewelry/artefacts for Hallmarking like, licence, solder, undesirable elements, existing marking, 4 marks, damage, hollow items, advanced stage of manufacture, fineness etc

•        Check the identity of customer against the BIS License list available.

•        Ensure that each item has adequate space for hallmarking and that there are no markings on the items. However, the item may have jeweler’s identification

•         If space is found inadequate return the item to the customer.

•        Collect the lot for Hallmarking after checking as per Annexure E 1 of IS 15820.

•        Issue acknowledgement with delivery date and time mentioned.

•        Deliver hallmarked and rejected Jewelry and cornets/silver chloride against production of receipt when the customer comes for taking delivery.

•         Issue invoice and collect necessary charges.

•  If jewelry is to be dispatched, then place hallmarked jewellery, rejected jewellery and cornets/silver chloride in separate bags with proper tags/labels and placed in a box of rigid material with cotton wrapping inside along with invoice.

•         Persons with purpose other than assay and hallmarking should be confirmed by reception only and be directed to the Managing PROPRIETOR or Quality Manager. Employee concerned will be called to the reception for meeting with such visitors.

                                                                                                      

 INSTRUCTIONS FOR XRF

• Start XRF Analyser in the morning, allow warm-up time, Check the XRF machine using the reference standards.

• Receive the Jewelry along with the job card giving details of jewelry type, quantity and weight.
• Segregate the jewelry according to the type of ornaments (Example Bangles, chain, Rings etc.).

•       Based on the declaration of the jewelry, screen each piece for purity on XRF as per the recommendations of the XRF machine manufacturer and presence of prohibited elements/metals such as cadmium, ruthenium and Iridium in gold articles/artefacts and lead and cadmium in silver articles/artefacts. In case of long and heavy pieces with variation identify the location of the lowest purity.

•       Reject the jewellery if it is (a) not homogenous; (b) very different from the declared purity; (c) not at sufficient advance stage of manufacturing or all the parts are not in position, and (d) presence of elements prohibited as per IS 1417 or IS 2112. 

•         Segregate the lot based on results obtained as follows and keep jewelry in trays/boxes/bags identifying the purity with the help of colored tags/labels   RED-REJECTED,  will be  WHITE  Marginally Pass GREEN – Pass (more than 1 ppt. below the declared value) for example in the case of 916,  items will be ‘RED’ if above than or equal to 911 but below 915, ‘’WHITE between 915 and 917 and ‘GREEN’ above 917

•       In each purity identify the item (s) with lowest purity by tagging

•        Items having presence of Ir, Ru, Cd or those different from the lot or more than 5 ppt below the declared value are to be separated with indication of the same so that these are not sampled or tested further

• Return the segregated lot to the Quality Manager
• Enter results in the XRF section of the Job card.

INSTRUCTIONS FOR SAMPLING

• ·                Keep the sampling tools in ready to use condition

• ·           Collect the jewelry for sampling from the Quality Manager in separate plastic boxes/ polythene pouches segregated into homogenous lots based on purity and type and pattern of the jewelry along with necessary instructions regarding the method of collecting the samples form each lot.

• ·         Sample size will be as per the approved sampling plan of BIS (refer ANNEX D & E of IS 15820-2009)

• ·            Collect required amount of samples from each lot. Ensure that the item with the lowest purity is included in the items from which sample is drawn

• ·                For cast items take cut samples from the spruce left by the manufacturer. In the case   of identical and homogenous articles take samples at random. From soldered items take samples from any place from the body of the item including soldered joints. For non-homogenous items like necklaces prepare samples by scrapping or cutting from different places

• ·                Make effort to take about 500 mg samples without damage to the jewelry. In case it is not possible or when the number of items is more take composite sample of required mass by scrapping 10mg or more of samples from each jewelry. Ensure that the ratio of composite sample prepared is appropriate to the size and the weight of the jewelry.

• ·                Take Minimum 500 mg weight of sample and maximum weight 1 g and in exceptional cases sample of size up to 125 mg is also taken in case of gold and about 3g in case of silver.

• ·                The method of collection of the sample should be recorded in the Job Card and the Sample Envelope/ Assay Sheet along with the weight. Note on the pouches the code number and the first alphabet of the color of the tag e.g. ‘W’’ for    ‘WHITE’’, sampling method and item to indicate the categories from which the samples were taken·   Identify the sample and record on the sample envelope/ assay sheet and return to the Quality Manager in small pouches along with the jewelry.

                             

INSTRUCTIONS FOR OPERATION OF BALANCE

•         The balance shall be  kept on a vibration free stand./table

•       Maintain the room temperature below 30 ⁰ C.

•        Check the level of the horizontal surface with spirit level.

•        Check the balance with any one dead weight once a day.

•      Reset the tare weight with weighing pan.

•      Keep track of servicing due dates.

•         Clean the machine regularly.

•       Do not disturb the position of the balance.

•              Ensure only authorized personnel use the balance.

INSTRUCTIONS FOR WEIGHING

•        Detailed procedure is as per IS 1418 in case of gold. Prepare two proof assay samples of about 150mg each and add copper proportionately to the expected amount present in the majority samples

•         Prepare samples in duplicate for assay between 125 mg and 250 mg (± 0.01 mg),so that the approx. mass of gold in samples is around the same as that in  the proof gold sample

•         Place the sample in assay grade lead foil. If the sample weight is less than or around 200 mg use 4 g of lead. For more than 200 mg sample use 6g lead,

•         Add silver 2.3 to 3 times the weight of fine gold present in the sample. Sample Weight x 0.916 (OR DECLARED fineness) x (2.3 to 3) and in case fineness is 990 ppt or more, remember to add 20 + 5 mg of copper to the samples also.                                             

•         Fold them into balls of 10 mm diameter.

           

  

INSTRUCTIONS FOR CUPELLATION & ANNEALING

• ·        Place the samples in the pre-heated cupels in the left to right order  and charge them at 1050ºC to 1100ºC in the furnace, maintaining oxidizing atmosphere.

• ·        Place the proof assay gold too in the same manner noting down the placement of   the samples and check gold in the assay register.

• ·        Record the time on the Board

• ·        Allow the samples for cupellation inside the furnace for 25 minutes. Note the time of ‘cut off’ for reducing the temperature. 

• ·        After the oxidization is complete cool the buttons formed, remove from Cupels and clean it with a hard nylon brush.

• ·        Flatten the buttons with hammer

• ·        Anneal the flattened button at around 700⁰C

• ·        Roll them to 0.12 to 0.15 mm thick strips

• ·        For identification and traceability number the strips using punches

• ·        Roll them to form loose cornets, keeping the dirty side up and numbered side out

 INSTRUCTIONS FOR PARTING

• ·                   Place the cornets in parting tray

• ·                   Take enough Acid 1 (sg=1.2  /  200 Acid 300 Water) to dip the cornets in a beaker and place it on the hot plate.

• ·                   The quantity of acid shall be adjusted so that the samples are fully immersed in acid during the test.

•                   Immerse the parting tray in the acid when the temperature is around 90⁰C,

•                  Boil gently for 15 minutes or when fumes stop emanating,

•                   Decant, wash with warm water and dry,

•                   Take enough Acid 2 (sg=1.3 /  300 Acid 200 Water) to dip the cornets in a beaker and place it on the hot plate.

• ·                   Immerse the parting tray in hot acid,

• ·                   Boil gently for 15 minutes or when fumes stop emanating,

• ·                   Decant, wash with warm water till free from silver nitrate and dry,

• ·                      Place the basket/tray in muffle furnace at 700 - 750ºC for 5 minutes.

INSTRUCTIONS FOR FINAL WEIGHING AND CALCULATION OF PURITY

                   After cooling weigh the samples

• ·        Calculate the Delta in the following manner:

∆ = ∑(Initial Check Gold Weight- Cornet Weight of Check Gold)

                     Number of check Gold Samples        

•                         Calculate the purity of the test piece with the following formula

         W=     (m₂ + ∆)X 1000         All Weights in mg

                                 m₁

               m2 - Weight of Cornet, m1 - Weight of Sample

Difference in two samples tested       ≤ 0.5 – Satisfactory testing

                                                       >0.5 discard and repeat test

Pass Jewellery which has average fineness of two samples ≥ declared fineness in case of satisfactory testing. In case the fineness is 990 ppt. or more, the ∆ for proof samples run in parallel should not differ by more than 0.04 mg. If it is more, then repeat the assay samples ≥ declared fineness in case of satisfactory testing

 

INSTRUCTIONS FOR MARKING

·        The Quality Manager to take the jewelry from the safe along with relevant details like identity of the BIS licensee and give the jewelery to the Laser Marking In-charge to mark in BIS approved sizes in case of conforming jewelry the following:

i)                   The BIS Standard Mark

ii)                Purity in carat and fineness (parts per thousand)

iii)              Assay Centre’s identification mark/number

iv)              Jeweler’s identification mark/number

·        The marking process will be as recommended by the manufacturer of the laser marking and all the security procedures will be strictly adhered. The Q Mgr/ Managing PROPRIETOR will check that the marking is in order.

·        In case of non- conforming jewelry ‘O’ will be marked or returned without marking.