Understanding the Use of 9ct versus 18ct Gold
- Tuesday, 30 May 2017 17:48
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In gold, the higher the carat / karat (sometimes abbreviated to “ct” and “K”) the higher the purity of the gold is.
If everything else is equal, such as weight, the higher the carat number is, the more expensive the gold will be.
This sometimes leads into questions as to why a jeweller might use18ct not 22ct/24ct and why on some 18ct pieces, there might be fittings of 9ct. This is easy to explain!
Gold is a very soft metal in its natural near 100% pure form (24ct). In fact, it’s so soft that it’s often impractical to make jewellery out of it. Other metals need to be added for strength.
Most jewellers consider 18ct to be the highest purity level that is a compromise between getting as much gold in as possible while giving the item enough strength so as to offer day-to-day robustness and longer-lasting durability. That’s why 18ct is often used as an international standard.
However, even though 18ct has strength, the metal might still not be quite hard enough to cope with daily use stresses in certain situations. Let’s take a hypothetical example – a brooch with a back pin.
In some cases, the surrounding of the piece might be in 18ct gold but the pin itself, due to the wear and tear it might suffer being hooked into its locking place, might have been made in 9ct or even base metal for greater strength.
Almost all our jewellery, such as pearl earrings, is made of 18ct gold. For durability’s sake in some cases, we may use 9ct for our accessories or for some styles, sterling silver.
We’re always more than happy to talk about gold purities and the differences between them. Please call us if you’d like further information.