Testing Gold the Archimedes Way


Wealthymatters.comI’m sure most people have heard the Archimedes story.He was the Greek guy who got out of his bath tub and ran,naked, down the street,shouting Eureka!Eureka ! I’ve Found It !

Just to refresh memories,here is the story:

Archimedes was a Greek scientist who lived in ancient Syracuse . The King of Syracuse wanted a gold crown made. So he gave some gold to a goldsmith to have one made. After few days, the goldsmith brought the finished crown to the King. The King had the crown weighed. He found weight of the crown to be equal to the weight of the gold he had given the goldsmith . However the color of the crown made the King suspicious. He believed that the goldsmith had pocketed some of the gold he had been given for his own personal use. The King wanted to find out the truth. So he asked his court scientist Archimedes to find out how pure the gold in the crown was.Obviously Archimedes could not melt down the new crown to determine its purity.So to find a solution Archimedes thought about the problem day and night. One day,while he was preoccupied thinking about this problem, he proceeded to take a bath. He was so preoccupied that he failed to notice that the water in his bathtub was already full to the brim.So as he got into into the bathtub ,a large quantity of water flowed over the rim . Archimedes noticed this and had a brainwave . He was so excited to have at last found the solution to the King’s problem that he jumped out of the bathtub,and ran naked down the street, shouting, “Eureka! Eureka!” Eureka in Greek means ‘I have found it.’ Read more of this post

Acid Test For Gold


All that glitters is not gold .Assaying determines just how much of that glitter is gold.

wealthymatters.comThe simplest way in which jewellers roughly estimate the purity of gold is by using a touchstone.This method has been in use since ancient times.A touchstone is a small tablet of dark stone such as fieldstone, slate, or lydite which has a finely grained surface on which soft metals like  gold leave a visible trace. Because different alloys of gold have different colours , depending on the different metals added to the gold and their quantities , the test sample can be compared to samples of known purity to estimate the gold content of the sample.Additionally, the fact, that the trace from the test sample will react differently to specific concentrations of nitric acid or aqua regia, can be used to estimate the quality of the gold.Unfortunately using a touchstone involves scratching the sample and each time the test is performed a tiny bit of gold is lost.And the results obtained by this method are not considered conclusive.

wealthymatters.com    non destructive testingTo avoid scratching gold,especially finished jewellery, we can use  X-Ray Fluorescence Spectroscopy (XRF) which is a non-destructive technique used to identify and determine the concentrations of elements.This is the technology used in the carat meters,like the picture on the right, found in places like the Tanishq showrooms. But carat meters only assesses the metal 5 mm from the surface . So they can detect only surface adulterants.Also the machines do not identify a metal unless a sample has been fed (calibrated) into them.This is why for a long time iridium and ruthenium adulteration went undetected in India.

 The only fool-proof method of determining the purity of gold is to go in for a fire assay. This is the method used in various BIS certified labs to conclusively establish the purity of gold.Unfortunately it is a destructive test. Read more of this post

Gulf Gold Bars – Caution


wealthymatters.comHere is an article of interest for all those who by gold bars from the Gulf.It appeared in TOI in August’10. 

 Purity of gold a big concern for jewellers

MUMBAI: After having detected the presence of platinum group metals in certain 24-carat gold bars imported from a few Middle Eastern countries, a leading jewellery industry body has urged the government to install sophisticated photosynthesising machines at each of the airports through which gold is channelised into the country. According to the trade, there are less than 4 such machines in the 150 hallmarking centres across the country.

“Over the past few years, we have been finding that certain 24-carat gold bars imported from some Middle Eastern countries contain traces of platinum group metals such as iridium and ruthenium,” said Vinod Hayagriv, chairman of All India Gems & Jewellery Trade Federation (GJF). “In light of this, we have asked the government to install photosynthesising machines, which cost over Rs 1 crore a piece, at customs in each of the cities’ international airports.”

Mr Hayagriv confirmed that though the incorporation of such metals in gold bars was limited to miniscule volumes of imported gold, the trade had to be “forewarned” of their likely presence. He was speaking at the launch of Swiss-made Milleret watches by Veeline Jewels & Watches at the recently concluded IIJS 2010, a business-to-business trade show organised by Gems & Jewellery Export Promotion Council.

Gold melts at 1063 degree celsius but the process begins at 800 degree C. Iridium and ruthenium melt at 1900-2000 degree C and can be melted along with gold. While gold starts melting at 800 degree C, ruthenium remains unmelted (the melting process begins at 2000 degrees C) in the form of a globule in some block of gold. As it remains unmelted the total weight of gold — the yellow metal is sold on weight — goes up. Read more of this post

The Dirty Truth About Indian Gold


wealthymatters.comHere is an article that appeared in the TOI in Jan ’09.If you invest in Indian gold jewellery,this article might just persuade you to have a fire assay done on your hoard to determine its fineness.

ALL THAT GLITTERS IS NOT GOLD 

Your wedding jewellery may not be as pure or as precious as you think it is. Several goldsmiths across India have taken to adulterating the precious metal with iridium and ruthenium,and are getting away with it, as until recently the metals failed to show up on all purity checks. It’s an alchemist’s dream, and the practice is becoming increasingly commonplace if you go by the stocks of the ‘duplicate’ metals at even the smallest of karigar workshops.

Both iridium and ruthenium belong to the platinum family of metals, and when mixed with gold, do not form an alloy but sit tight in the yellow metal.

What makes the adulteration even more alarming is that the metals do not replace silver and copper, which are added to the gold during the jewellery-making process to harden the soft, malleable yellow metal. As Saumen Bhaumik, general manager (Retailing) at Tanishq put it, “The two metals manage to camouflage as gold.’’

TOI tested several pieces of jewellery, and all had some amount of either iridium or ruthenium lurking inconspicuously with the gold. A 22-carat gold bangle bought in 2003 from a century-and-a-half-old jeweller—who has since then expanded from Mumbai to other parts of the country—when tested at the Indian Institute of Technology-Bombay, had 3% iridium in it.

A gold chain bought from a shop in Bangalore in 2002 when tested at another citybased centre had 2.39% ruthenium, while a pair of earrings from Kerala was found to be adulterated with 4.65% of iridium.

On an average, a piece of jewellery or a bar of gold contains nearly 5-6% of the adulterant, and manufacturers—wholesalers and retailers across India—are aware of how rampant this notorious practice is. Consumers, however, are the biggest losers as they have been kept in the dark. Read more of this post

Chinese Gold


wealthymatters.comHere is a piece of news I came across.Since so many Indians consider shopping in HK these days I think the following clipping  is a must read.

Fake gold scam hammers Hong Kong jewellers

 With the gold price sitting at record highs, Hong Kong jewellers and pawn shops have been hammered by one of the most sophisticated scams in which hundreds of ounces of fake gold were traded in the market.

The gold-mad city has woken up to a massive scam as investigators discovered that at least 200 ounces of fake bullion, worth about $250,000 have been traded at the island`s fabled jewellery souks so far this year, Financial Times reported.

“It’s a very good fake”, said Haywood Cheung, president of the Chinese Gold and Silver Exchange Society, Hong Kong’s hundred year old gold exchange, highlighting how criminals are developing new techniques to commit an age-old fraud.

 Though officially only 200 ounces of fake gold was recorded as traded, Cheung estimated that 10 times that amount might have infiltrated the retail market. Describing the swindle as ” one of the most sophisticated scams to hit Hong Kong gold market in decades”, the Financial Times said it has come when the price of gold has soared to record highs of $1,400 an ounce.

In one case, executives discovered a pure gold coating that masked a complex alloy with similar properties to gold. The fake gold included a significant amount of bullion — about 51 per cent of the total — alloyed with seven other metals: osmium, iridium, ruthenium, copper, nickel, iron, and rhodium. Read more of this post

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