Tjaša Malalan

On Gold

Tjaša Malalan

Everyone knows that gold is one of the most popular precious metals – no need to explain that. The same applies to the fact that people have been using gold to adorn their bodies for more than 6000 years – nor do we wonder at the fact that this noble metal was one of the first currencies and that for a long period of time, the value of money rested on gold. 


But that’s far from being everything: did you know that the amount of gold that is hidden in the Earth’s core would suffice to coat the whole planet with a 45-centimeter-thick gold coating?

Gold is ideal for jewellery-making not only because it does not oxidise and is hypoallergenic, but because it does not lose its shine with time and because it is highly malleable.

We mix other metals with gold to increase its strength or to change its colour. The fineness of gold, the ratio of gold parts to other metals in the alloy, is quantified in units of parts per 1000 or karats.

The quality of gold in your jewelry can be identified by a hallmark, which is stamped onto every product. Hallmarks are commonly found on less visible parts of the jewelry.

Quality of Gold by Percentage, Fineness and Karats



Percentage of Gold
Fineness
Karats
100 %1000 fine24 karats
91,7 %917 fine22 karats
75,0 %750 fine18 karats
58,5 %585 fine14 karats
41,6 %416 fine10 karats
Gold is excavated on all continents of the world. West Africa, Australia and the Dominican Republic have the largest gold deposits.
Symbol
The chemical symbol for gold is Au and it is derived from the Latin word aurum. Pure gold melts at 1063 °C.
Karat
The karat is a unit used for measuring the weight of diamonds as well as gold; however with gold, we measure its purity and not its weight.  
Colour
In order to change the color of gold, we add different metals to the alloy. If we add palladium the gold turns white; if we add copper it turns into different shades of pink; while if we add copper and cadmium, the gold turns slightly green
Ore
Gold, along with other precious metals, is found in the form of ore below the surface of the Earth. One ton of ore contains approximately 6.5 grams of gold.
Weight
One litre of gold weighs approximately 19.3 kg.
Coloring
Gold can also be colored with surface processing: by utilizing the process of electrolysis, we can apply a layer of rhodium or ruthenium onto the surface, which turns the gold white or black. We can patinate the gold with various alloys that contain sulfur or oxygen. With a layer of oxides on the surface, we can even color the gold blue.
The total quantity of gold mined so far is approximately 160,000 tons – the amount that could fill more than three Olympic swimming pools.
Malleability
We can beat one ounce of gold (31.10347687g) into a more than 80-km-long thread or spread an extremely thin sheet with an area of more than 9 square meters. 
Electronics
Because of its excellent conductivity and resistance to corrosion, gold is widely used in electronics. In 2015, Apple gained approximately one ton of gold from discarded mobile phones, worth around 38 million euros
Blood
Every person has about 0.2 mg of gold in his or her body, which is mostly dissolved in blood.
Olympic medal
An Olympic Gold medal contains only 1.34% of gold.
The Largest
The largest gold bar weighs 250 kg; the largest gold coin, made in Australia, weighs 1000 kg.
Housewives in India own 11% of global gold reserves, which is more than the US, Switzerland and Germany own combined. More than 200 billion euros worth of gold lies under the streets of London; that is about a fifth of the gold reserves of the world's governments.