Hardness of Gold, - misconceptions!
By: Stuart Noble
The Scottish Heirloom Company, like most jewellery manufacturers, produces our product range in Sterling Silver, 10 kt (karat), 14kt and 18kt gold.
When choosing items in gold, customers are often reluctant to choose the higher karats of gold. This is not due to the higher prices, but they have heard that 18 kt gold is softer and will wear away faster than 10kt. Is this correct? - The answer is a definite "NO!".
This is usually a surprise to many customers and also to, strangely enough, many jewellery stores sales staff..
This incorrect belief is kind of understandable, as it is fairly well known that pure (24 kt) gold is too soft to be used in most jewellery and has to be alloyed with other metals to make it harder and more durable. It is then believed that the more of the other metals that are added to the gold, the harder it becomes. The sales staffs in some jewellery stores, that mainly sell cheaper 10 kt gold items, also sometime state this idea in order to help sell the 10 kt items.
Here are the approximate maximum "Vickers" hardness values of the various Karats of gold. The higher the number, the harder the alloy.
10 kt ............ 170
14 kt ............ 180
18 kt ............ 230
Sterling silver .. 65.
As you can see, contrary to most people's expectations, 18 kt gold is the hardest of the alloys.
The term 'Karat', also spelled 'Carat' comes from the Greek word for the seed of the Carob tree. These seeds are very uniform in weight and were once used as standard weights when measuring very fine items. The term Karat or Carat is now also used as a measure of the purity of gold, as a number of the parts of gold by weight in every 24 parts of a Gold alloy. The other metals included in most gold alloys are usually copper, silver and zinc.
24 kt is pure gold, with no other metals.
18 kt is 18 parts gold and 6 parts total of silver and copper. (75.0% gold)
14 kt is 14 parts gold and 10 parts total of silver and copper. (58.3%)
10 kt is 10 parts weight of gold to 14 parts of other metals. (41.6%)
Because Gold is so much heavier than the other metals, the actual amount of gold, by volume, in the different alloys is much less.
10 kt = 41% by weight and 24% by volume.
14 kt = 58.55 by weight and 39% by volume.
18 kt = 75% by weight and 61% by volume.
Which is best?
We always produce items, which are designed to be Heirlooms and as such are made to last for many generations. Whether it is 10, 14 or 18 kt, it is certainly not going to wear out. My favourite is, however, 18 kt gold. It is the hardest wearing, looks good and is almost 40% heavier than 10 kt gold, so feels as gold should, - solid, and heavy!
10 kt and 14 kt alloys also make very nice items.
It usually comes down to price, with 10kt gold being around half the price of 18 kt gold.
The choice is yours!!
About The Author:
The Author, a Scot, is Stuart Noble, the founder and Chief Executive of the Scottish Heirloom Company, manufacturing jewelers, specializing in the production of Scottish Family Crest Jewellery. You can publish this article if the author's byline is included and all links are hyperlinked.