It's easy to forget sometimes that what you know isn’t what everyone knows–I realized this recently as I struck up a conversation with a new friend about gold purity. I’m essentially talking about the difference between 14k gold and 22k gold and what exactly a karat is anyway.
To begin at the beginning–what is a karat? It is a unit for measuring the purity of gold. 24 karats is pure gold–there is no higher karat than that! This means if you slice a pie into 24 wedges, all of them are pure gold. My kind of pie!
You might be wondering if this is the same as a carat–as in a 2 ct diamond ring? To be confusing, no. A carat is a unit of weight measurement–it comes from the carob seed which we once used to measure the weight of jewelry and stones. In the UK they have only one word, however, carat there describes both stone weight and gold purity! American jewelers in the 1850s thought to call it a karat when referring to gold specifically, and the distinction makes sense. They both have the same roots but while meaning shifted over time, the word stayed the same.
So back to karat golds, anything below 24k is a mixed metal (called an alloy). 18k gold is 18 parts pure gold and 6 parts other metals–usually copper and silver. And so on down the line. The reason we mix gold with other metals is because pure gold is quite soft and will have a hard time keeping its shape over time. And also because the higher the gold content the higher the price, lower karats offer durability and affordability.
24k = pure gold. Divine! Some make jewelry with this and while the gold will never degrade, it’s form probably will. Ancient jewelry can still be found in 24k gold but it’s often misshapen.
22k = often stamped “916” it is 91.67% gold and is the standard in India. (for them gold is a wearable investment). There are many classical goldsmithing techniques that are only possible with gold this pure. Still somewhat soft, but suitable for every day wear and is a bright yellow.
18k = often stamped “750” it is 75% gold. This has long been the standard of fine jewelry in the US and Europe, it’s still got a rich yellow color but is stronger than 22k. It is a dream to work with from a jeweler’s perspective.
14k = usually just stamped 14k. This is 58% gold and has a more subtle yellow color. This gold has become more popular as gold prices have gone up and can still be considered fine jewelry. The other metals in the mix can be silver, copper, zinc, and nickel, so people with metal allergies might need to ask questions. This is a nice hard metal that will last without breaking the bank.
10k = only 41.7% gold, there’s actually more silver in this gold than gold! This gold has a similar color though to 14k and is a really tough metal that will certainly hold up. This is the lowest legal karat able to be sold in the US, in the UK you will find 9ct gold.
You might be wondering about other colors of gold you’ve seen–rose gold, white gold, green gold. These might have more copper content for rose, more silver for green, more nickel or zinc for white. A jeweler can create their very own mix or alloy. And just FYI I can have my pieces cast in any of the karat golds–though the casting company I typically use works up to 18k.
And there’s your gold lesson for the day! Did you learn something new? Is there a karat you prefer? Since I am in this for the love of the materials, I’d have to say the higher the karat the better. But I can also be quite happy wearing any type of gold, and even mixing metals as I do daily.
Thanks, as always, for being here!