Heard the news of the real-life discovery that some diamonds come from outer space? We kid you not. Carbonados take their name from the Portuguese verb carbonizar, meaning to burn, and are charcoal-coloured diamonds found exclusively in Brazil and the Central African Republic, though never in mining fields.
It's this oddity that led geologist and diamond expert Professor Stephen Haggerty to theorise that carbonados were not created like conventional diamonds, whereby ordinary carbon was subjected to immense heat in the earth's mantle millions of years ago. Rather, Haggerty believes carbonados formed when stars rich in carbon exploded and rained onto the land now known as Brazil and the Central African Republic.
It all sounds a little fantastic, but Haggerty and his team at Florida International University recently managed to prove it... almost.
Using infrared radiation to analyse the make-up of the diamond, they found trace elements critical to an extraterrestrial origin. "The presence of hydrogen in the carbonado diamonds indicates an origin in a hydrogen-rich interstellar space," Haggerty explains.
A diamond from space presents a unique selling proposition (USP) never before seen, but before marketers start salivating at the prospect of a campaign, carbonados never feature in jewellery design - they are so rare that only two and a half tonnes have ever been found and their surfaces are so hard that it takes 6,000 pounds of pressure per square-inch just to dent one.
Black diamonds of a different kind have been making a small but significant indentation in the jewellery world over the last decade, and their rise to fame is quite intriguing.
These days, coloured diamonds are very much in vogue - due once more to the persuasive power of promotion - and black diamonds are attracting their own special audience of appreciators.
A natural black diamond is actually a badly-fractured diamond that has had its fractures filled with graphite or other black minerals that give it a dark appearance.
The most famous example of a naturally-black stone is the Black Orlov, a 67.5-carat beauty that has graced the necks of late Russian princesses and today's Hollywood starlets. Legend has it the diamond was once part of the 195-carat Eye of Brahma that was stolen from an Indian shrine centuries ago by a Hindu monk. The diamond was re-cut into three separate gems in an attempt to break a horrible curse that its theft incurred; nevertheless, several owners of the Black Orlov have leapt to their deaths in the years that have followed.
The truth about black diamonds is that the vast majority used in jewellery today are actually yellow and brown diamonds treated using radiation or heat to achieve a black colour. This is because natural blacks are few and far between - most of them actually range between dullish grey and gunmetal. Yellow and brown diamonds provide an easy solution because they are in abundance and able to achieve a pure, uniform black when treated. Hence, they are greatly sought-after for use in jewellery.
Gemmologist and jeweller Darren Daley has been working treated-black diamonds into his designs for about a decade.
Daley sells an average of six pieces a year from his gallery in country Victoria.
"They really are a bit of a niche," he explains. "You won't sell them by the barrel-load, but there's a little more black-diamond jewellery around at the moment. I think it's because white metals are popular and black stones look really effective when set into white metal. Black diamonds aren't that nice by themselves but they look lovely when they're used to make contrast pieces."
Daley's method is to contrast the black gems with their white counterparts in pavé designs for rings; he also greatly admires jewellery that combines black diamonds with Tahitian pearl.
"It's the black-and-white concept that appeals to people," he says. Black diamonds sell to those who are looking for something out of the ordinary - people who are bored with the usual stones."
Makers Mark creates several black diamond pieces in Melbourne each year.
"There are heaps of smaller black diamonds around, and they tend to work extremely well in the pavé designs," says Maker's Mark jewellery designer Shaylee McKenzie. "We don't really go down that glitzy road though. We'll use black diamonds because they are rarely seen and we are known for doing the unusual."
The retailer is currently working on a set of tuxedo studs that feature black diamonds set into white gold.
"In reality, you would use them because they are effective, not because they are precious. It's not the dollar value, but the interest value that makes the black diamond a notable stone.
"We'll introduce them to a client if a gem merchant has provided us with some interesting stock," McKenzie adds, "but it's never really because a client requests them."
Diamond merchant Edward Swaab isn't surprised by this. "People don't know they exist," he says. "It's only the boutique designers and retailers that actually point them out to the consumer. There's not a lot of value marketing black diamonds because they are a fraction of the price of other diamonds and they are perceived for the male market, which is very small," Swaab says.
Swaab, who runs the Certified Diamond Network in Parramatta, added black diamonds to his list 10 years ago.
"The thing with black diamonds is that they are usually heavily included. Their quality is not right up there and they have had a difficulty attached to them with cutting and polishing. But technology has greatly improved over the last decade and we have a much-better finished product," he explains.
Swaab receives one to two dozen requests for black diamonds each year and he believes there are a handful of Sydney importers who hold onto a certain amount.
"There's definitely a point of difference value in them," he says. "Someone might feature them in the shop window to draw interest, and that is always good promotion. But black-
diamond jewellery will only really work for the middle-to-upper boutique market and I think it will always remain that way."
Black diamonds don't get the starring roles that are reserved for white stones, yet they are destined to make cameo appearances in unusual, one-off pieces of jewellery. For jewellers with an imagination and an open-minded client base, black diamonds are both relatively-available and versatile. Marry them with good-quality white diamonds, pair them with pearls or treat them as beads.
With starkly-contrasting white gold, stainless steel and platinum still in fashion, now is as good a time as any to experiment with the richness of the blackest of gemstones.