Red diamonds are beautiful, with rich red colour and the brilliance and sparkle of a clear diamond, jewellery wearers and diamond connoisseurs love red diamonds.

Red diamonds are the most valuable and rarest of all diamonds; buyers of red diamonds are happy to pay hundreds of thousands of pounds per carat. We think of clear diamonds are rare, but for every 10,000 clear diamonds, there is only one coloured diamond. Fewer than 30 pure red diamonds are known to have been discovered throughout history. Most red diamonds are tiny at less than one carat in size.

The largest red diamond is just 5.11 carats, the Fancy Red Moussaieff Red Diamond found in Brazil in the 1990s.

Red diamonds are so rarely seen that most jewellers will have never handled a genuine, natural, red diamond!

What Is A Red Diamond?

A red diamond is exactly the same as a colourless diamond, except for the colour. Experts are not entirely sure how the red colour is formed. It is thought that, like pink diamonds, the colour is due to a process called plastic deformation. Diamond crystals, still fluid, were subjected to immense pressure while being forced to the surface of the earth. The intense pressure caused slight changes to the crystalline structure of the carbon atoms leading them to absorb green and blue light frequencies, leading the diamonds to solidify with a deep red colour. If this explanation for the colour is correct, then red diamonds may be an exceedingly rare form of pink diamond.

Red Diamond Colouration

Most red diamonds are not entirely red but have their colour modified with a secondary colour caused by trace impurities. The costliest red diamonds are always those with the least secondary hue and the deepest saturation.

Red diamonds are most often found with a secondary colour such as brown, orange, or purple. Red is never seen as the secondary colour to any other fancy coloured diamond. The most pleasing and sought after secondary colour is purple with orange and brown secondary colours having much less value than red or purplish-red gems.

Unlike other diamond colours, except black and clear/white, all diamonds have just one colour intensity called, in the GIA coloured diamond grading system, 'Fancy'.

Red Diamond Clarity

When most diamonds are graded using the 4Cs, clarity is often regarded as being the most crucial factor. With coloured diamonds, the colour is the critical factor with buyers seeking the best, deepest, most pure colour. Because of the way that red diamonds were formed, most have excellent clarity with VS1-SI2 being typical. Due to their rarity, most buyers choose red diamonds based upon the colour and size; clarity has little effect upon the stone's value.

Red Diamond Carat Weight (Size)

Like other coloured diamonds, larger sizes are much rarer than smaller ones. Most red diamonds are smaller than 1 carat. Only 5 red diamonds are recorded as being larger than 5 carats.

Red Diamonds Fluoresce

Almost all red diamonds fluoresce under UV light. Some clear diamonds fluoresce and, when this happens, it decreases the appeal and value of the stone. In the case of red diamonds, fluorescence has no adverse effect on the price. Fluorescence is used as an identifier for genuine red diamonds because no synthetic diamond exhibits the effect.

Where Do Red Diamonds Come From?

Red diamonds are found in locations where pink diamonds are found. There are no recorded cases where a red diamond was found where pink diamonds had not been discovered nearby. Most red diamonds are found in the Argyle Mine in Western Australia, others have been found in Brazil, Russia and African mines.

Treated And Synthetic Red Diamonds

Natural red diamonds are so rare and costly that they are beyond the reach of most people. Because they are so beautiful, there is a demand for a similar but lower-cost alternative. Methods have been developed to treat natural diamonds to make them red. This is usually accomplished using irradiation followed by a high-temperature treatment called annealing, some diamonds are coated to attain their final red colour. Irradiation and annealing is regarded as a permanent process while coating is less durable because of the potential for scratching or chipping of the coating.

Synthetic, lab-grown red diamonds exist; their creation mimics the natural process of creating a diamond, but at a far faster speed.

Protect Your Red Diamond Investment

When you buy a red diamond, you should be told if it is a natural, treated or synthetic gem. To protect yourself and your investment always seek out a diamond grading report from a trustworthy grading lab such as the GIA. The GIA will not grade synthetic stones; their reports will record if the diamond's colour is natural or the result of colour treatment.

If Red Isn't Possible Then What Can Be Done?

Unless you are a rich celebrity or billionaire, then a real red diamond of any significant size is probably unattainable, but there is an option. The option is still far from cheap but is more accessible to mere mortals. Given that red diamonds appear to be a very dark form of pink diamonds, choosing a very dark shade of pink, with the right cut and polishing, can look like a red diamond. One thing is for sure if your wealth is adequate to pull off that trick, then nobody is going to argue with you about it!