The Metal Guide

Buying Guide

Gold

Gold is a rare precious metal, with a remarkable combination of chemical and physical properties. The name gold derives from the Old English word for yellow, 'Geolu' and gold is the only yellow metal. Pure gold does not oxidize under normal conditions, meaning that it will not corrode or tarnish. Gold's special physical properties of high electrical conductivity and chemical inertness make it an excellent and reliable conductor, particularly in harsh environments with extreme temperature ranges. Gold finds uses in many technical applications, in the manufacturing of PCB boards and in electrical circuits. It is amazingly malleable and therefore lends itself especially for jewellery making.

Gold Purity

The purity of gold is measured in karats. The term “Karat” is different from the unit of measure “Carat”, which is used to measure gemstone weights. The purity of gold in karat terms determines its value. “Karat” is derived from the word “Carob” and stems from ancient trading times, when the seeds of the Carob tree were used as a reference weight to measure the weight of precious metals. Pure gold is very soft and malleable and therefore needs to get alloyed with other metals to achieve the strength and hardness that is required to create useable objects. The mixing of gold with other metals also changes it’s colour. 24 karat is 100 % pure gold, and is more expensive and less durable than gold that is alloyed with other metals.

Gold Purity For The Most Commonly Used Karats:

24 Karat - 24K Gold with 100% purity

22 Karat - 22K Gold with 91.6% purity

18 Karat - 18K Gold with 75% purity

14 Karat - 14K Gold with 58.33% purity

24 karat gold is soft pure gold without any alloys and features a deep yellow colour with a rich luster. Gold of lesser karats (22K-14K) are all alloyed with a combination of silver, copper, nickel and zinc. These alloying elements add strength, but they can also impact the depth of the colour. Any gold alloy combination below 14 Karat will render a dull and pale colour. For beauty, durability, and wearability 14K and 18K gold are highly recommended.

Gold Color

In its pure form, gold has a high metallic yellow luster, but when alloyed with other metals, such as silver, copper, zinc, nickel, platinum, palladium, etc. it displays various colour shades like white, pink/ rose and green.

Yellow Gold

Yellow gold is the most frequently used gold colour and is considered timeless colour. It is usually alloyed with silver and copper. Depending on the karat gold (14K, 18K or 22K), the color of yellow gold may vary from a softer shiny yellow to a bright rich yellow luster. This is due to the varying alloy combinations. Yellow gold is the ideal gold colour for setting warm coloured gemstones. For instance when setting emeralds it is recommended to set the gemstone into a yellow gold setting, as the warm colour of the gold will make the emerald appear deeper green and more precious.

White Gold

White gold is harder than yellow gold and features a bright band shiny luster. It is often alloyed with a high percentage of silver, or a mixture of other white precious metals, such as palladium. Some white gold alloys are created by the use of nickel. This metal is known to cause allergies, which manifest themselves in the form of skin rashes and itchy skin. Tanishq uses nickel-safe white gold alloys that meet international consumer protection standards. White gold is never fully white and to improve the whiteness it is electroplated with rhodium. Rhodium is a platinum group metal which features an exceptional whiteness and hardness. Rhodium plating therefore not only makes the jewellery piece look more white, bbut it also provides the surface with a layer of increased hardness, which in turn provides a higher degree of scratch-resistance.

Pink / Rose Gold

Pink gold or rose gold does not exist in nature. Instead it is created by mixing the yellow gold content with copper, silver and zinc. The higher the copper concentration in the alloy is, the deeper will be the rose colour of the resulting gold. Rose gold is available in a number of purities. The higher the concentration of the non-gold components of the alloys are, the paler is the resulting rose gold colour. The colour of rose gold ranges from a deep, almost copper-red colour, to a light radiant blush pink depending; on the recipe of the specific gold alloy. Pink gold alloys are very fashionable and are the preferred gold colour for fancy colour pink diamonds as well as pink sapphires and tourmalines. The surrounding pink gold colour in a setting bounces its colour reflection onto the gemstone and makes it appear more deeply saturated and hence more valuable.

Green Gold

Green gold is a popular gold colour in the US and supports fair skin tones very well. It is not particularly popular in Asia, because the cultural preferences there are more geared towards deeply saturated gold tones. Green gold is an excellent base alloy for fired enamels, because it consists only of precious metals and hence doesn’t tarnish under the high firing temperatures required for the creation of fine enamel surfaces.. For the creation of green gold, pure gold is alloyed with silver to achieve a green gold colour. Green gold is often used as a contrast colour in multi-colour jewellery designs and adds a spot of a different and unusual colour to an otherwise rather traditional appearance.

Platinum

Platinum is an extremely rare precious metal that is even more rare than gold. It is usually more expensive than gold, but on various occasions in recent history, ruled by the laws of supply and demand, it has been traded lower than gold. Platinum is found in only a few locations around the world, mainly in, South Africa's Merensky Reef, Russia's Ural Mountains and a few small mines in the US and Canada.

Platinum is a strong, dense metal, with a high specific gravity. It is nearly double as heavy as 14 karat gold and features some very unique attributes that make it a very desirable jewellery metal. Due to its softness paired with great strength, platinum doesn’t wear away which means that the original weight that a jewellery piece has at the time of purchase will remain the same, even after decades of intensive wear. This is also the reason why large diamonds are frequently set in platinum, as the prongs will remain strong and the exceptional whiteness of platinum makes the diamond appear more white and hence more valuable. Platinum is incredibly strong, for instance a wire of the thickness of a hair can bear the weight of 1 kg. Platinum is used in jewellry, laboratory equipment, electrical contacts, dentistry, and automobile emissions control devices. The highest amount of the available platinum production is used by the automobile industry followed my the medical sector. Platinum for the use of jewellery only consumes about 5% of the annual platinum production.

The annual worldwide production of platinum amounts to about 160 tons, compared to about 1500 tons of gold. The mining and refining processes are complex and labour intensive. In order to refine one single ounce of platinum from mined ore, about 10 tons of ore need to get processed for ore extraction. The refining process from rock to final platinum ingot involves many mechanical and chemical steps- some of which have to be repeated up to five times until the desired purity is reached. Since platinum is usually found together with platinum group metals (ruthenium, rhodium, osmium, iridium and palladium) which all have very similar properties, the separation of the individual metals is very time consuming. The complete platinum refining cycle takes five months.

Platinum Purity

Platinum, is the purest of all the precious metals used for the fabrication of premium jewellery and is commonly alloyed into a purity of 95%. Platinum has an very bright and white luster, particularly when alloyed with ruthenium. Platinum is harder than gold with a hardness of 4-4.5 on the Mohs hardness scale, equivalent to the hardness of iron, whereas gold has a hardness of 2.5 on the Moh’s scale.

The purity of platinum is not expressed in Karats, but in parts of thousands. Pure platinum is 1000 of 1000 parts pure, whereas the most common alloy used in India is 950/1000 parts pure. Expressed in percentage, this equals a purity of 95%. While some countries permit platinum alloys of as low as 585/1000 parts, the Indian quality standard is set at a minimum of 950 parts.

Platinum is hypoallergenic and fully tarnish-resistant. Platinum jewellery maintains its colour (no plating required), brilliance and weight, even after long and intensive years of wear and is the nearly fully maintenance free, particularly compared to gold and silver, which are both precious metals that need to get re-polished in regular intervals to maintain their shine and luster.

Platinum Versus Gold

Platinum is known for centuries, but in the current high purity form it is a recent precious metal, since the technology of melting and refining platinum to today’s high purity standards is less than 200 years old. The metal has gained increasing popularity because of its amazing strength and appeal. However it has remained an exclusive jewellery material, because its high density, combined with its high purity commands a much higher price, than for instance 18 Karat white gold. Platinum will cost approximately double the amount of an identical design made in 18 Karat white gold.