Legal Metrology Department

[Perfection]

• Weigh Bridge : They are of Pit type and pit less type with capacity varying from 10 to 200 ton.

Load Cell is the heart of an electronic weigh bridge. A load cell is a transducer that is used to convert a force into electrical signal. It senses the strain and convert it to mV and the micro controller based Digitizer converts the signal received to weight. Display is of LED/LCD 7 segment type reading weight in kg/t. Using an RS 232C port, the data can be send to a computer for taking printout. Password protected software is used for calibration of the Weighbridge.





The Weigh Bridge verification Mobile Kits are efficiently utilized by the Legal Metrology Department for testing the accuracy of Weigh Bridges in the Kerala State. Each kit is provided with verified test weight of the range of 1 ton to 50 kg with a maximum of 12100 kg. A folding type hydraulically operated crane is mounted on the test kit to lift these weights. The time duration for this verification has been reduced by 3 to 4 hours. The main advantage of this kit is that the verification is quick and highly accurate. A user fee of Rs 5000/- per unit has been fixed by the Government for utilizing this facility.

[Perfection]

• Hallmarking

Pure gold (Au) is soft and very malleable. It has a melting point of 1064 deg. C. As gold is too soft, jewelers mix copper, silver, palladium to make gold ornaments. Purity of gold is measured in Carat (ct). So basically, a gold ornament is an alloy. The word carat is etived from the Greek word kerátion. The spelling karat (k or kt) is used in US and Canada

It is said that more than 40% of gold (969 t of gold/annum - World Gold Council report 2011) in the world is purchased by Indians. Hallmarking system in gold ornaments was introduced in the country by the year 2000, under the certification scheme of BIS (Bureau of Indian Standards). For this, recognition is given to Hall Marking and assaying centers for hallmarking of gold jewellery as per relevant Indian Standards (IS 141).

Gold ornaments



Goldsmith's company was headquartered in London at Goldsmiths' Hall from whence the English term "hallmark" is derived. In 1478, Assay office was at Goldsmiths' Hall.

Hallmark is the symbol, which indicates your gold jewelry is genuine gold. Pure gold (100 %) is made of 24 karat and is practically impossible. Electrolytic refining can produce 999 gold. The number associated with Gold Hallmark varies with gold purity. A 9 carat gold item will have 375 in it. A 14 carat item will have 585 on it. On an 18 carat item, 750 will be put. 916 can be seen on 22 carat gold (91.6% gold). 80% of the gold jewellery is of 22 ct.

Hallmark is done using punches or by Laser marking machines. Hallmarking is done on gold, silver and platinum.

Jewelers own Hallmarking centres (working on the guidelines of BIS) and are putting the mark of their own gold ornaments. In Kerala, public can know the purity of their gold ornaments from Gold Purity Testing Laboratory at Kakkanad Legal Metrology Bhavan, Kochi (Phone-0484-2423180) and it avoid cheating in terms of purity of gold.



99.5 % pure gold bar

Gold Purity Tests

Earlier Acid test kits were used to find the purity of the gold (Fire Assay Method/ Cupellation). A small sample is taken randomly and is lost during the test. The test result tells only about the purity of the outer layer of gold in the ornament. Now Electronic testing kits, X-ray fluorescence (a non-destructive technique) etc. are widely used to find gold purity.