Precious Metals 101 : Sterling Silver

August 12, 2017

Precious Metals 101 : Sterling Silver

Many people are familiar with the names of the precious metals used to create fine jewellery but not everyone knows what happens to them before they get transformed into that shiny new ring, pendant, bangle or pair of earrings.

Here begins a crash course in everything precious metal. Having the info on precious metal alloys may help you make an informed decision in regards to your next piece of jewellery so read on friends. There is quite a bit to know about metals and jewellery so we will feature one metal per blog. Let's start with......

Sterling silver: 

A popular metal for both fine jewellery and fashion pieces, sterling silver can be a complicated alloy. Traditionally sterling silver was made using a percentage of pure silver ( 92.5% to be exact) and adding 7.5% of copper to the mix to give a little bit of extra hardness and durability. Pure silver can be used in jewellery and has a very beautiful finish but it is a bit softer as opposed to sterling with the addition of the copper.

It gets a little more complex when other metals are added to the mix for various reasons. Nowadays, science has helped us to identify other metals that can help with the oxidisation  ( or tarnish ) that sterling silver is prone to, like the metal germanium. Adding additional metals such as Nickel to the alloy can be problematic for some people. 

Nickel seems to be a very reactive metal for alot of people causing irritation that can range from mild to quite severe. Sterling silver alloy produced in Australia should never have nickel added to the mix but it is commonly added to fashion jewellery that is produced overseas. Pure silver actually contains antibacterial properties and can accelerate the body's natural healing processes. This is why you can now buy some first aid items such as dressings and bandaids that contain pure silver. If you have had a reaction to sterling silver in the past it is likely that the reaction was caused by the inclusion of nickel into the alloy and not by the silver itself. If in doubt always ask if the silver jewellery is nickel free.

In our workshop we prefer to have full quality control over our metal alloys as much as possible so we choose to alloy our own sterling silver using the traditional 92.5% pure silver with 7.5% copper. 

All precious metal should be marked with a stamp to identify it's purity called a hallmark. In Australia the hallmark '925' is the most commonly used mark to identify sterling silver. This relates back to the 92.5% of pure silver used in the alloy. It is important to note that just because a item has a hallmark it does not mean that the item is not a fake. We see plenty of pieces of cheap, base metal pieces of jewellery that have been silver or gold plated and then hallmarked as the real deal. Any properly trained manufacturing jeweller will be able to test a piece of jewellery to quickly and easily determine the purity of an alloy. Unfortunately with jewellery, what you see is not always what you get so if in doubt, check with a qualified professional.

Another mark you may come across when talking about silver is AG. This is the chemical symbol for silver. Try to remember your periodic table now! Or just google it, thank you google! 47 is the atomic number for silver and it is also called by the name Argentum. It falls in the group of transition metals on the periodic table and it has the highest electrical and thermal conductivity of any of the metals.  

What does all that mean for jewellery? The thermal conductivity is probably the most relevant. Silver heats up super fast and holds the heat for longer. When repairing silver jewellery that is set with gemstones we need to be careful to properly protect and insulate the gems from getting too hot and in some cases certain repairs may not even be possible. This is also a problem with gold jewellery set with certain gems but silver in particular because of this high level of thermal conductivity. 

This concludes our chemistry lesson for today, hopefully you will find some of this info useful and maybe you learned something new today. Next time I will explain yellow and rose gold. Stay tuned for further blogs on white gold, platinum, palladium and coloured golds like purple and green. That's right, purple gold is totally a thing that I did not just make up!

 




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