What is a carat?

18 carat gold Diamond Dot earrings

 

Firstly, let's clear up the k versus c conundrum. Karat and carat can both be used to describe the fineness of gold - karat being more usually used in America.

Carat - and never karat! - is universally used to describe the weight of gemstones.

 

Ok. So let's talk about gemstones. The word carat is derived from the Arabic for 'bean pod'. People needed a way to measure the weight of their gems even hundreds of years ago, so they turned to the carob tree.

The carob's seed weighs about as much as the smallest gemstone and so this became the base unit for weight. The seed was called a carat and so the name was born. A stone weighing approximately the same as one seed was said to weigh one carat.

In the early 20th century - as carob beans can presumably vary, as well as not being that widely available - the weight of one carat was set at 200 milligrams - or 0.2 grams. 

 

 

When it comes to gold carats it's all about the gold content.

Pure gold, in its freshly mined form, is not usually used to make jewellery as it is a relatively soft material.

So, to increase its durability and make it more suited to everyday wear it is alloyed (mixed) with other harder metals...In the case of yellow gold, mainly silver and copper.

The gold content is measured in parts, or 'carats', with 24 carat gold being 100% pure gold.

24 carat gold is pure gold - 100% gold.

22 carat gold is 22 parts pure gold -  91.6%.

18 carat gold is 18 parts pure gold - 75%.

9 carat gold is 9 parts pure gold - 37.5%.

These percentages correspond to the UK hallmarks for gold: 916 for 22 carat gold, 750 for 18 carat and 375 for 9 carat. You can read more about the UK hallmark and its meaning in my blog post here.

14 carat rose gold and 18 carat yellow gold bespoke wedding rings

 

But which is best?! Well, the higher the gold content, the softer the metal. 22 carat gold although widely used in Indian jewellery is not considered suitable for most jewellery due to its relative softness.

18 carat gold is beautiful - to work with and to wear. It has a beautiful colour and is durable enough for most styles of jewellery.

9 carat gold is much harder than 18 carat but conversely, this doesn't mean it's more durable. It's a bit like comparing glass with plastic. Glass is much harder than plastic...but much more breakable. Likewise 9 carat gold while harder, is in fact much more brittle than higher carat gold.

It often comes down to budget in the end though, and the cost of gold may well be a factor when deciding. Prices are constantly rising...but fortunately gold remains a good investment as it's a relatively scarce resource plus it holds its value well. 

And surely that's just a very good reason to buy lots of gold jewellery! 

9 carat multi birthstone necklace, commission