Sterling silver is one of the most popular materials that are used to make jewellery alongside white gold and yellow gold. What you might not know about it, is that silver jewellery does not contain 100% silver. Silver alone is far too soft and malleable to be used everyday, therefore, it is alloyed with other metals to increase its durability. An alloy is a metal made by combining two or more metallic elements.
We’re going to take you through the whole rundown of the silver manufacturing process right from deep in the ground to hanging pretty from a chain around your neck. For a product that is so readily available, you may be surprised at the length of the silver making process!
How Sterling Silver is Made:
Mining
To begin, silver ores are mined from the earth. They can be mined in two different ways; open pit or underground. The open pit method uses heavy machinery to mine deposits near the earth's surface, whereas underground mining tunnels deep underground to extract the ores. In fact, silver is only present in about 5 parts out of a million (think of a million red smarties and only 5 of them contain silver). The difference between silver and other precious metals is that it is often mined as a by-product of mining other metals like copper, lead, zinc and even gold. There are actually very few mines that solely extract silver.
Processing
Once the silver is taken to the surface, it is subject to crushing and fine grinding, including a flotation process that separates the silver from waste rock particles, mineral concentrates and silver bearing galena. The most popular method is the Jameson process, which was developed in Australia. It involves mixing together ground-up ore, water and other special chemicals and constantly agitating them in banks of flotation cells. Air is then blown through the mixture and fine silver-bearing galena particles stick to the bubbles which rise to the top of the container in a froth consistency. Waste sinks to the bottom, and the froth is skimmed off, leaving silver-bearing sulphide concentrate - which contains anywhere from 800 grams to 1 kilograms of silver per tonne of concentrate.
The silver concentrate is then partly melted to combine the fine particles into lumps and remove some of the sulphur. It is then smelted in blast furnaces and drossed (removal of trace copper and impurities) to create crude lead metal. Silver is recovered when crude lead is refined to high purity. Hence, the molten lead is poured into an upright container called a ‘kettle’ that undergoes a series of processes, until a dore remains (a silver-gold-copper alloy). Finally, the dore undergoes more smelting, resulting in the removal of copper and the separation of high purity silver and gold.
You can learn more about Australian mining and processing of silver here.
Sterling Silver as an Alloy
Fine silver, which is 99% silver, is very soft and malleable, therefore it is usually alloyed with copper to increase its strength. Sterling silver is made by melting pure silver (which has a melting point of 960.5ºc) and combining melted copper (which has a melting point of 1093ºc). After all of this, the resulting sterling silver is not reactive to everyday materials like oxygen or water at ordinary temperatures, therefore, your skin will not turn green from regular wear and it can last a very long time. Not only this, but the product has the wonderful look of silver with increased strength and ductility, which means that it can be more easily worked with to create jewellery and other objects.
You may have seen the stamp ‘925’ on your sterling silver pieces. This stamp stands for the 92.5% silver content, with the remaining 7.5% being made up from copper. Most genuine sterling silver items of jewellery will have this stamp.
The silver process is anything but a simple one, however, technology has come a long way in recent years which has streamlined the process. Next time you pick up your favourite sterling silver rings or pop in your sterling silver earrings, you’ll be able to look back on the amazing processes that were undertaken to make that item! Sterling silver is our favourite material for jewellery for so many reasons so why not take a look through our amazing catalogue of products?