Thanks for sending us some more questions! We noticed that a few of you were interested in the metals used in jewellery making. Why do we use certain metals over others? Why are some metals more expensive than others? Why do metals tarnish?

Let’s answer these questions we’ve received and learn some things about metal along the way!

Question 1: What are the main metals used in jewellery making?

 One downside to note is that many of the newer materials can’t be resized like traditional silver and gold

Gold and silver are the main metals used in jewellery making and have been for thousands of years; valued for their rarity, workability, lustre, and resistance to oxidation. Over time several other metals started being used in manufacturing, for example platinum and its cousin palladium are used for their strength and unique whitish lustre that doesn’t need plating to stay white. Recently metals such as titanium, tungsten and stainless steel have been introduced for increased strength and resistance to scratching, which are useful for people who use their hands a lot in situations where traditional metals could be damaged. Makers are now experimenting with metals like tantalum; used for its extreme strength, shatter resistance and unique greyish colour and niobium; used for its array of beautiful colourations when anodised. On top of all this there are also non-metals such as silicon, resins and ceramics. Whilst these new materials have interesting properties that make them suited for different purposes, one downside to note is that many of the newer materials can’t be resized like traditional silver and gold.

Question 2: Why is gold more expensive than silver?

 The expense of metals is based on rarity. Gold is simply more valuable because there is less of it in the world. Here is an interesting visualisation for you. Let’s say you took all of the gold ever mined in history (from jewellery to circuitry to gold bars) and put it in one place. Now let’s add on all the gold there is yet to be mined out of the Earth and added it to this pile you had made. How much do you think you would have? The answer is not that much, it’s estimated to be around 250,000 metric tonnes, just enough to fill about 4 Olympic-sized swimming pools. If we compare this to silver, it’s estimated that nearly 1.7 million metric tonnes has been mined to date – that’s nearly 30 olympic-sized swimming pools so far, and that also not taking into account what there is yet to be mined out there.

Question 3: What is the most expensive metal and why?

 If it takes about 10g of Platinum to make a wedding ring, we’ve only got enough for about 1 billion for them!

 This is a fun question to answer! Let’s take the example of a plain, 6mm wide men’s wedding band in a T (US size 10) and see how much would this cost to make in a number of metals: 

Platinum wins this race hands down. 

Why is Platinum so expensive? If we go back to our analogy before:

Silver –1.7 million metric tons (estimated) mined so far.

Gold – Estimated 250,000 metric tons (estimated) on Earth.

Platinum – There is only 16,000 metric tons (estimated) on Earth! If it takes about 10g of Platinum to make a wedding ring, we’ve only then got enough for about 1 billion for them!

Side Note - A bit of Platinum trivia

Platinum has an interesting history, it was initially discovered by Spanish Conquistadores in the rivers of Ecuador around 1590. Thinking that this strange whitish metal was just silver (plata in Spanish) that hadn’t “ripened”, they named it little silver (platina) and threw it back into the water! It wasn’t until around 1750 that platinum was recognised as a new element, and it wasn’t until the 19th century that it was used in jewellery making.

Platinum has some remarkable properties. It is extremely dense (around 60% heavier than gold) and extremely resistant to fading or tarnishing. It is also very pliable yet strong once formed and unlike gold, it does not need to be mixed with a high concentration of other metals to make it suitable for wear.

Question 4: Why does silver tarnish?

 This is an interesting question and to answer it, we are going to have to do some chemistry – don’t panic, this won’t be like high school, I promise!

  If you looked at a piece of metal under extremely high magnification, you would see a lattice of atoms all bonded together and held tightly in a geometric pattern. Metals react to the environment but it is usually only the very topmost layer that reacts and their structure means that they can’t usually undergo very fast chemical reactions – like you would see when you mix vinegar and baking soda together.

  That black substance we know as ‘tarnish’ is a mix of silver sulphide and copper sulphide that forms by the reaction of the silver metal and gases in the atmosphere that contain sulphur (the most infamous is the ‘rotten egg gas’ or hydrogen sulphide). Other sulphur gases can come from clay, certain foods, other people, paint, plaster, wood, water and even volcanoes!

The rate at which tarnish forms can vary depending on the concentration of gas; from months for a piece kept in a controlled environment like a museum to minutes for a piece closed in a container with a freshly sliced boiled egg (a fun experiment to do, but not with any sentimental or prized silver pieces!).

  So how to prevent tarnish? You can read our jewellery care guide for our recommended tips. If you have a piece of silver jewellery that is tarnished and want some cleaning advice, read our other blog article here for some instructions (especially if it has gemstones in it).

Question 5: What is an alloy?

 An alloy is simply a mix of two or more metals that when combined increase the strength and durability of the overall material. Fun fact – there are some natural alloys out there such as electrum (alloy of gold and silver), bronze (alloy of tin and copper) and meteorites (alloys of iron and nickel).

A 2700-year old cup from Idalium in ancient Cyprus made from electrum, a natural alloy of gold and silver. (Public domain)

Most of the precious metals are very malleable, meaning that they bend and scratch very easily. In fact, pure gold can be scratched with a fingernail and would be very unsuitable for making jewellery out of. So what are the most common alloys we see in jewellery making then?

 Sterling Silver (925) – The 925 in Sterling Silver refers to the amount of silver present, in this case 92.5% of the total weight. The other 7.5% of the metal can be a few different things, with copper being the most common addition.

 Gold – What we refer to as pure gold is 24ct gold, i.e. 100% gold with no other metal. The most common alloys you will see are 9ct (375 or 37.5% gold) and 18ct (750 or 75% pure gold). Gold is naturally yellow and depending on the metals added, that’s how you get rose gold and white gold. Interestingly the ‘recipes’ of other metals added to make coloured gold can vary between manufacturers and this can cause slight colour differences. So when you look at alloyed white gold (that is not rhodium plated) from one manufacturer it might be yellower or grayer than another.

Bonus Question - What does it mean when jewellery is plated?

We kept this question with this post because many people often get confused with the difference between alloys and plating.  

Instead of a mix of metals, plating involves putting a thin microscopic layer of one metal over the surface of another metal. For example gold plated jewellery is where a microscopic layer of gold is put onto various metals like brass, bronze, stainless steel or even sterling silver. Gold plating reduces the cost of the pieces while giving it the gold jewellery look and can even be done in a rose or white gold.

Did you know that you might already be wearing plated jewellery without even knowing it? Most sterling silver and white gold jewellery is plated with a layer of rhodium which gives it that very white appearance. If you’ve noticed your white gold jewellery getting a bit dull and yellowish and cleaning doesn’t fix it, you can have it re-plated in rhodium to bring back the white shine.

We hope that this has answered your questions and hope that you've learned a few things. If there is anything else that we can answer for you, please leave a comment or message us directly and we can include it in a future post!