On hearing "black gold" you might think of films or bands with the same name, or of commodities like coal or petroleum. Recently, scientists at the Tata Institute of Fundamental Research used gold nanoparticles to create a new material they named black gold, which absorbs light and carbon dioxide. But here we look at the black gold used in jewellery.
The original colour of gold is yellow, but new methods give us gold jewels in pink, blue, green and white. There is also genuine black gold jewellery, and it is gaining popularity. Among black jewellery (black tungsten, ceramic, titanium, carbon fibre), black gold is the most valuable because of its gold content.
How black gold is created
- Gold mixed with cobalt in a 3:1 ratio gives an alloy with a black coating on its surface.
- Electroplating gold with rhodium gives a shiny, polished black surface.
- The most durable version uses a femto-second laser, which manipulates the surface of the gold with high focused energy to give a pitch-black hue.
What it is worth, and caring for it
The value of black gold depends on the percentage of gold it contains; the other metals used do not add to or detract from the worth of the gold itself. A black pendant or ring is a style statement and pairs beautifully with gemstones like sapphire, amethyst or ruby.
Caring for black gold is a challenge. Clean it only with a non-abrasive jewellery cleaner. Over time the plating wears off and reveals the gold beneath, known as "bleeding," and re-plating can be costly. Instead, if you have a bleeding black-gold piece, bring it to Aaradyaa Gold, sell it and get instant cash for the gold it contains.