Gold has been used for various purposes since ancient times, and it endures due to many of its characteristics such as ductility, malleability and its obvious attractiveness. While the metal is used in ornaments and jewellery to a large extent, it is rarely used in its purest form.
Being extremely ductile and malleable, pure gold is very soft and can melt and change form when exposed to heat for long durations. As a result, gold jewellery is likely to lose its shape when worn. To prevent this and to also make it more economical (since the yellow metal is also quite expensive), it is usually mixed with other metals for it to be used in jewellery.
Gold by itself is a deep yellow colour when mined in its most pure form. When mixed with alloys though, its colour changes based on the concentration and mix of alloys being added to it. The alloys are added to different purities of gold viz., usually 18k and 22k gold.
Given below are some of the more common metals added to gold
Silver is the most common addition to gold. Silver is similar in properties to the yellow metal, being one of the noble metals (metals that do not oxidize easily or corrode). A gold and silver alloy makes the resultant metal more elastic and stronger. The addition of silver to gold gives the metal a whitish tinge, depending on the amount that is added.
Silver is considered a moderate bleacher of gold, making the ‘white gold’ that results a good metal for jewellery. Usually 21k gold is used for alloying with silver.
Coper is a naturally-occurring metal with a distinctive reddish pink colour. Though mostly used in electrical wiring and in coins because of its high thermal and electrical conductivity, it is also added to gold to enhance the metal’s colour and strength.
Copper is widely used as a gold alloy because of the colour it imparts to the finished metal. Copper alloyed gold has a rose sheen and is frequently used when malleability is desired. Copper is usually added in conjunction with silver to make the alloyed gold stronger but also more pliable.
Rose gold is the term given to gold jewellery that has a high concentration of copper added to it, usually in the proportion of 75% pure gold and 25% of copper.
One of the most widely used metals, zinc is known for its anti-corrosive properties. It is used across fields for a variety of purposes from medicine to technology. With regard to jewellery, it is added to a gold alloy to reduce the intensity of the colour especially if copper is also alloyed. Adding zinc changes the colour of alloyed gold to a deep yellow.
Palladium is a naturally-occurring rare metal known for its lustrous silver colour. Used mostly in electronics and medicine, it is also added to gold alloys. Gold alloys with palladium are commonly referred to as ‘white gold’ because of the bleaching effect the metal has on gold.
In addition to the metals listed above, there are other metals such as cadmium, manganese etc. depending on the desired tint to be added to gold. So gold rate is high.