Colourless diamonds have long been an engagement ring fixtures, sparkling in the centre of gorgeous solitaires and three-stone beauties. But today’s brides are less conventional than those of generations past. Not only have coloured gemstones been trending, but more and more, we see a rise in coloured diamonds.
If you haven’t explored the world of fancy colour diamonds, we’re eager to introduce you to silvery greys, deep purples and sunshiny yellows. The story behind these colours is fascinating and goes back millions of years.
How Are Coloured Diamonds Formed?
Like colourless diamonds, coloured diamonds form deep within the earth in the area called the mantle. Intense pressure changes the molecular structure of carbon by crushing its atoms together and moulding them into a new, lattice-like configuration. To accomplish this change, temperatures must reach about 1500 degrees centigrade, and the necessary pressure would be like 4,000 grown men standing on your foot.
Volcanic rock called Kimberlite forms deep within the earth. As it moves upward to the earth’s surface, it creates a “pipe” that carries the molten rock, mantel fragments and diamonds. The journey spans about 200 kilometres.
Coloured diamonds form when foreign particulates become trapped during the crystallisation process, altering the chemical process. Depending on the foreign particulate, the diamond can turn any number of beautiful colours: pink, blue, red, green, orange, yellow, violet, brown and even black.
Check out the unusual origins of some of today’s trendiest diamonds.
Orange and Yellow Diamonds
Warm and bright, these diamonds owe their lustrous colour to one element: nitrogen. While the diamonds formed deep below the earth’s surface, nitrogen atoms absorbed blue light in the stone, creating a yellowish hue.
Brown, Red and Pink Diamonds
These fancy coloured diamonds didn’t have run-ins with elements like nitrogen while they formed; they experienced an unusual combination of intense pressure and heat, which caused distortions in the lattice that absorb green light. The light resulted in a permanent brown, red or pink colour.
Gray and Blue Diamonds
The serene beauty of grey and blue diamonds stems from their encounter with the element boron during their formation. Boron bonds to the stone’s carbon and absorbs red, yellow and green parts of the colour spectrum.
Violet and Purple Diamonds
Scientists don’t completely agree on the causes of violet and purple colouring in some diamonds. Some theorise that the colour results from a particular crystal distortion. Others think the presence of hydrogen may be responsible for the regal colouring.
These diamonds made it almost all the way up to the earth’s surface before acquiring their gorgeous colour. Along their journey, they absorb radiation, which causes them to reflect a green hue by absorbing yellow and red light.
The Scarcity of Coloured Diamonds
As you might expect, natural coloured diamonds are rare (they make up roughly 2 percent of the total diamonds on the market today). And since they’ve been rising in popularity in recent years, they can be quite expensive. If you’re pining for a yellow diamond engagement ring, what are your options?
In addition to natural coloured diamonds, you might consider colour-treated diamonds. These are natural diamonds (not created in a lab) that receive treatment to enhance their colour. Often, colour-treated diamonds initially had a low score on the colour scale (meaning, they weren’t colourless). Pale yellow diamonds might be enhanced (to a vivid yellow) or even changed to brown or red diamonds.
The method for colour treating diamonds is called HPHT (High Pressure High Temperature). Interestingly, HPHT is also used to produce lab-created diamonds from scratch because it mimics the pressure and heat that naturally occurs deep underground.
Yellow diamonds have been trending recently, and several factors may influence this trend. Yellow gold has made a comeback, and yellow diamonds provide a harmonious counterpart to the buttery precious metal.
Additionally, yellow diamonds are the most common coloured diamonds, so they’re easier to find. Rarer colours such as pink and red, yield very high prices.
Selecting Coloured Diamonds
As with any other diamond purchase, ask to see a stone’s certification before making a purchase. Choose a colour you love, but also pay attention to the 4C’s: carat, clarity, colour and cut.
Choose a metal that complements the diamond, whether you’re seeking a monochromatic look or a bold contrast. Many coloured diamond engagement rings include colourless diamonds on the band or as halos.
Protect Your Coloured Diamond
Unlike most precious stones, coloured diamonds can genuinely be considered investments. Their value continues to rise, and because of their scarcity, they not only hold their value but increase substantially.