what is gold?
Gold is the most well-known precious metal. It is the chemical element with the symbol Au (the Latin word is aurum) and it has the atomic number 79, making it one of the higher atomic number elements that occur naturally. In its purest form, it is a bright, slightly reddish yellow metal. Throughout history it has been appreciated for its beauty and scarcity. Also referred to as ‘the king of metals’. Traditionally, gold in the universe is thought to have formed by the r-process (rapid neutron capture) in supernova nucleosynthesis, but more recently it has been suggested that gold and other elements heavier than iron may also be produced in quantity by the r-process in the collision of neutron stars.
what is an alloy?
Because of the softness of pure (24k) gold, it is usually alloyed with other metals for use in jewelry, altering its hardness, ductility, melting point, colour and other chemical properties. This metal mix is called an alloy. Gold alloys, typically 21 ct, 18 ct, or 14 ct contain higher percentages of copper or other precious metals like silver or palladium in the mix the lower the carat. At Oogst we usually work with the 14 ct gold alloy. By request, we also create jewellery in 18 ct gold. Historically 9 ct is not considered gold in The Netherlands and consequently not used.
Fun fact: In the old days golden coins were made of pure gold, which is very soft. That’s where the habit originated to bite a coin to test if it is real.
In The Netherlands we have ‘de Waarborg’, the Assay Office, an institute that checks the gold content in a piece of jewellery. They will test and stamp it with the right carat symbol. Pure gold will get a stamp with 999, 18 carat gold will get a stamp with 750 and 14 carat gold will get a stamp with 585. The number is representing the pure gold as a part of 1000 parts in the alloy. The other part is consisting of other metals like copper, silver or palladium. Therefore the alloy in 14 crt gold consists of 585 parts pure gold and 415 parts other metals, out of 1000 parts of the alloy. The added metals define the color of the gold.
These alloy proportions are calculated carefully and can be checked with aqua regia or with special x-ray equipment.
what kind of precious metals are there?
A precious metal is a metal that doesn’t get oxidized easily. For this reason precious metals are used to create jewellery. Gold and platinum will always look lovely and untarnished. Silver can get a little black after a while, but is easily polished. Non precious metals are for example copper, iron and sink.
All of the precious metals lined up: Platinum, Gold, Silver, Rhodium, Osmium, Palladium, Iridium, Ruthenium, Tungsten and Collodium. At Oogst we use Silver, Gold, Platinum and Palladium to create our jewellery.
what colour gold do we use?
By mixing pure gold with other metals you change the characteristics. This influences the alloy’s colour, hardness and ductility. At Oogst we work with 4 colours of gold. Yellow, rose and rosé gold are all made of pure gold mixed with silver and copper but in different proportions. And white gold. Until not so long ago white gold was an alloy of fine gold mixed with nickel, but because a lot of people have nickel allergy it has been banned from the market for 15 years already. At Oogst we work with the most precious white gold alloy made of fine gold and palladium. This mix gives it a beautiful greyish tone.
There are other combinations of metals possible. You could create greenish or purplish gold, but these are too brittle to create jewellery with.
From left to right the colours of 14 ct rosé gold, rose gold, yellow gold and palladium white gold.
is gold a sustainable product?
Yes and No. Recycling your own gold is lovely sustainable way to create a gold jewel. The mining and transport of gold is quite environmentally harmful.
Which is why we prefer to use ‘recycled gold’ for all our jewellery. This gold has been recycled locally in The Netherlands. Every goldsmith participates by collecting all their filings and leftover pieces and bringing them to be recycled. But other industries, and private individuals who exchange their gold jewellery for cash, contribute as well. All this gold is collected, cleansed and re-alloyed by our suppliers. This is called ‘urban mining’. Then the locally recycled gold is brought back to the market, so we can then create something from it.
Did you know you can also bring your heirloom gold to our studio, like an old necklace or a ring you inherited from your grandmother. We can melt it and re-use the gold or gemstones. Transform it from an heirloom to a showpiece!