What are the different types of gold? How is gold coloured? Do you understand gold purity?

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What are the different types of gold? How is gold coloured? Do you understand gold purity? Gold was first discovered as shiny yellow nuggets in streams all over the world. No doubt it was the first metal known to mankind. Its brilliance, natural beauty, and lustre made it enjoyable to work and play with.

There are many physical aspects of the yellow metal which are truly amazing. Gold is the most malleable (able to be hammered into very thin sheets) and ductile (able to be drawn into a fine wire) of all metals. It is so malleable that a goldsmith can hammer one ounce of gold into a thin translucent wafer covering more than 100 square feet only five millionths of an inch thick. It would be so thin that 1,000 sheets would be needed to make up the thickness of one newspaper page. Its ductility is equally amazing. One ounce of gold can be drawn into a wire 50 miles long!

Furthermore, you only need one ounce of this marvellous metal to plate a thread of copper 1,000 miles long.
Unlike a car, television, or house, gold is not something that greatly varies in its purest form. Gold found in ancient ruins from thousands of years ago technically (if we ignore the novel/antique aspect of it) has the same worth as a newly minted gold coin in present day IF they have identical weight and purity.

Gold Alloys

You might have heard of gold being described by a certain number followed by the letter ‘K’. This simply tells you how much actual gold is in the ‘gold’ jewelry or object in question. Something that is 24K gold is technically pure gold (although depending on the country, pureness of 99% is usually enough to qualify it as 24K). The K refers to the term ‘karat‘ or ‘carat‘ which is an ancient form of weight now used to determine the pureness of the gold in question. For example, 12K (which is half of 24K) would tell you that your ‘gold’ item has 50% actual gold inside it, with the rest being other types of metal such as copper and silver. So whatever the karat value of your gold, divide it by 24 and multiply by 100 to reach the % purity that your gold holds.

Coloured Gold: Gold is coloured by mixing it with different metals, Gold can take different colours depending on the metals it is mixed with.

White Gold: For gold to take a white colour, it must be mixed with a white metal such as nickel, manganese or palladium. Standard White gold is usually 14K of gold (58.5% purity) while the rest is divided as 21% copper, 7.84% zinc, and 12.73% nickel. White gold is often rhodium plated to give it a shinier, whiter   appearance.

Rose, Pink, Red Gold: Gold can take these colours when mixed with copper. The more copper in the alloy, the darker the tone of red that will surface. A common rose gold alloy composition is 18K (75% gold) mixed with 25% copper while a 50/50 mix of gold (12K) with copper results in what we would call red gold.

Green Gold: Green gold, otherwise known as electrum, is a natural forming alloy which combines gold and silver. The greenish colour varies depending on the exact mixture, but it’s usually  73% gold, 27% silver.

Blue Gold: 46% gold, 54% indium

Purple Gold: 80% gold, 20% aluminum.

Black Gold: 75% gold, 25% cobalt.

Gold Plating Options

To know what type of gold coating the jewelry has, look for the quality stamp on the metal. Without a quality stamp on the item, you will not be able to know the type of gold used – if the jewelry is gold plated, rolled gold plated, gold filled etc. There are several types of gold plating options that you may come across when buying gold jewelry. Below is a short description on what the different types of gold plating options actually mean.

Gold-Layered / Flash Gold Plating: Since there is no Federal standard for “gold layered”, gold-layered jewelry can in fact have a super thin gold layer! Flash gold plating is when jewellery is given a very thin coating of gold, just enough to give colour and even finish. It is commonly used to plate costume jewellery, and semiprecious gemstone jewellery, where the base metal may or may not be sterling silver.

Gold Leaf: Gold leaf is gold that has been hammered by hand into extremely thin layers and been wrapped (or glided) around the metal.  Usually 22K or 24K gold is used as thin gold layers/sheets to decorate art work and jewellery. You can recognise gold leaf jewellery by its irregularities of the foil surrounding the item.

Gold Plated / Gold Electroplated: Jewellery that is “gold plated” or “gold electroplated”  means that it has a very thin layer of gold onto the surface of the metal. The base metal can be stainless steel, or brass dipped into gold. Gold plating is a process known as electroplating that gives the jewel a gold-like appearance. To be named “gold plated” or “gold electroplated”, the gold layer needs to be at least 7 millionths of an inch thick and of at least 10k gold quality.

Gold Overlay / Rolled Gold Plated: Gold overlay or rolled gold plated jewelry has a thicker gold coating and is thus more durable over time. The gold content must be of at least 10K gold quality, but can be lower than 1/20 of the total weight. The base metal can be brass, stainless steel, or copper. It uses heat and pressure process to mix and bond the metals.

Gold-Filled: Gold-filled is a slightly misleading term since it is not actually “filled with gold,” but rather, its base metals are brass or copper covered by sheets of gold. It uses a heat and pressure process (bonding process) to mix and bond the metals together. The gold content must be of at least 10K gold quality and the gold content must be at least  1/20 (5%) of the total weight. The gold layer will not flake or peel off with reasonable care.

Vermeil: Vermeil (pronounced ver-may) simply means “gold plated sterling silver”. The difference between “vermeil” and “gold plated/filled is that gold vermeil jewelry has a thicker gold layer and uses sterling silver as its base metal. This is why vermeil is a better choice (compared to other gold plated jewelry items) for those with skin allergy. Vermeil is usually not marked, but if  gold jewellery is marked with a “925” stamp, it probably means that it is  gold vermeil. (The stamp for sterling silver is 925,.925, or the modern stamp S925. It stands for 92.5% pure silver and 7.5% alloyed metals.) Most of the jewellery at Lustre is vermeil, and these items are referred to on the site as “gold plated sterling silver,” or “gold plated silver.”

 

Visit Anaita Thakkar’s page to find out more about her work.

_{This post was first published on Lustre Jewellery blog and has been reposted on Executive Lifestyle with the permission of the author.}
^{Edited by Michelle Sarthou 
Image credit: Anaita Thakkar}

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