Black gold. Is there such a thing? Well, the short answer is “no”. Black gold is something that we are often asked for, probably because there are images of black rings all over the internet, and people (incorrectly) assume that black gold is a thing.
Alloys Give Us Different Colour Golds
Eighteen carat gold is an alloy that is three quarters gold. Pure gold is naturally a reddish yellow colour. So in 18ct. gold, three quarters of the alloy is yellow. The other metals used for the remaining quarter of the alloy are what give the metal its colour. So for white gold, in Australia, yellow gold is mixed with palladium. For rose gold, yellow gold is mixed with copper. There are other colours of gold alloy not commonly seen, such as spangold and green gold. And more again that are too brittle for use in jewellery (blue and purple gold)
Yellow gold alloy is a mix of gold, zinc and copper. We don’t use pure gold (24ct.) for jewellery as it is too soft. Some countries use 22ct. gold for jewellery.
In Australia, diamond engagement rings are usually made in 18ct. gold, although we do on occasion see some imported diamond rings that are made from 9ct. gold. This is not a great idea, especially if the ring is white gold. This is because, in 9ct., the alloy is too soft for a diamond set ring that is to be worn every day. Remember that diamonds are very hard! So if the alloy holding them in place is too soft, the diamonds will work themselves loose.
The Black Gold Look is Achieved By The Application of Surface Treatments
So how does black gold come into the equation? Surface treatments can be applied to gold to make it look black. Much like we rhodium plate white gold to make it look whiter, gold can have black rhodium or other metals plated onto the surface, to give a blackish appearance. Another method is to heat the gold. This also gives it a blackish look.
The trouble with heating and with plating, is that they are surface treatments only and do wear off over time. Because the underlying surface colour is so different, black rhodium really doesn’t look that great as it wears off. Blackening the ring through heating does look good, but it just doesn’t last.
Industrial applications are now being used to form black gold by creating nanostructures on the surface of the metal that makes the metal look black as it absorbs the light that falls on it. Unfortunately this is a bit too high tech for jewellery use at the moment.
So what are the options if you love the black look? Well, there is no great solution if it is a gold ring that you want. Gold is the traditional metal for engagement and wedding rings. And it is so for good reason. It is hard wearing. Eighteen carat gold is, for most metal colours, the most durable metal for a ring that is to be worn every day.
Maybe consider a ring that has been blackened with a surface treatment as a dress ring. Something that isn’t going to be worn all the time.
