Red diamond buyer's guide: All you need to know

In brief: The rarest of the rare, only a handful of true red diamonds are known to exist in the world. From its origin to its value, this guide will give you an insight on the properties of the most expensive colored diamond. Out of your league? Don’t worry. You’ve got a cheaper, conflict-free, and environment-friendly alternative: synthetic, lab-grown red diamonds.

Originating from mines in Africa, Australia and Brazil, the red diamond is known for its extreme rarity. It is the least common of all the fancy colored diamonds and the priciest. It is hard to come by a pure red diamond, devoid of secondary colors. According to the lab reports of Gemological Institute of America (GIA) over a 30 year period not a single lab report was issued for a diamond with ‘red’ as its color. The unbelievable rarity of a red diamond controls its exorbitant prices, making it less available to consumers, celebrities and non-celebrities alike. In this guide, we’ll have a look at what sets the red diamonds apart and how you could own one too.

  1. How is a fancy colored diamond formed?

Diamonds in general are made out of highly organized carbon. When these atoms combine flawlessly without imperfections or alterations, a pure, colorless and perfectly transparent diamond is formed. If there are glitches during the chemical bonding, the result is a colored diamond. For instance, yellow diamonds (the most common of fancy diamonds) are formed due to nitrogen present during its formation while blue diamonds are created due to the presence of boron.

  1. What causes the red color in red diamonds?

Red diamonds, on the other hand, are not formed due to the presence of a foreign element. Just like colorless diamonds, red diamonds too are made purely of carbon. What causes the color is a slight deformity in the crystal lattice of the carbon atoms. When light passes and bends through it, a ruby-like color is reflected.

  1. How are red diamonds graded?

Another quality that separates these precious red diamonds from other colored diamonds is how they are classified and graded when it comes to color. Because red diamonds are considered as coming at the end of the pink diamond spectrum, they are highly saturated and cannot be graded as dark pink or red pink. Generally, colored diamonds are further graded into their levels of intensity but red diamonds come in only one: Fancy Red.

Just like other colored diamonds, red diamonds can contain secondary colors. The most common ones are Purplish, Brownish, and Orangey. However, the stronger the red color, the higher the price of the diamond.

  1. Lab-grown (man-made) and enhanced red diamonds

These two options are much more affordable than natural red diamonds, but bear in mind that they are still pricey compared to other colored diamonds.

As opposed to natural diamonds that are created through geological processes, lab-grown diamonds are created through artificial processes. Lab-grown or synthetic diamonds are cheaper, environment-friendly, and conflict-free. Without destroying the ecosystem by extracting geologically-grown diamonds, synthetic diamonds are produced in controlled laboratory conditions that simulate the processes and properties of a natural diamond.

Enhanced red diamonds are created through the process of irradiation, a post-growth treatment to change a diamond’s color and/or its intensity. Through irradiation, lab-grown diamonds (which may be white, yellow, or blue) or natural white diamonds are bombarded with neutrons or electrons to change the structure of the crystal lattice, modifying the diamond’s color. The stone is then heated to achieve the desired reddish hue. It can be difficult to achieve the desired hue when treating larger stones.

Lab-created red diamond Vs Natural red diamond (price comparison)

  • This is a 0.75 carat enhanced red diamond listed for $4,125 on Dianer DiamondsLab created (man-made) red diamond
  • This is a 0.47 natural red diamond listed on for a whopping $235,100natural red diamond
  1. How to evaluate synthetic/enhanced red diamonds

The greatest advantage of buying synthetic or enhanced diamonds is that you have more options with regards to weight (carat), color, clarity and cut of the diamond. Below is a brief list of the considerations when buying synthetic or enhanced diamonds:


As a general rule, the higher the carat (weight), the more valuable the diamond is. Red diamonds in particular rarely come in great sizes. It is therefore safe to say that red diamonds are an exception to this rule. In fact, the largest known red diamond - the Moussaieff Red - is only 5.11 carats. All other true red diamonds are less than a carat in size. However, synthetic red diamonds provide more options and you may be able to find a slightly larger stone.

Color & Clarity

Clarity is not a significant factor when it comes to colored diamonds, but color is the most important aspect. You may want to pay attention to how red diamonds look in different lighting conditions when purchasing. For example, they look best in daylight and worst in fluorescent light.


A diamond’s cut can significantly affect how brightly it shines. The rule of thumb is to choose a cut that would maximize the light that passes through the diamond to better reflect its color. In the case of red diamonds, they come best in radiants and ovals that emphasize the red color. The round shape, in contrast, tends to lower the saturation.

  1. Choosing a good gemological lab is crucial

Whether you buy a synthetic, enhanced or natural red diamond, it is crucial to have a reputed gemological lab to evaluate the stone. The report will tell you the origin, grade, clarity, color and other critical information. Also, make sure that your gemological lab of choice conducts its process using modern, state-of-the-art equipment for grading and treatment.

The image below shows a GIA Report for an enhanced red diamond from Dianer Diamonds.

 Dianer diamonds red diamond lad report

Source: Dianer Diamonds

  1. Famous red diamondsMoussaieff red diamond

The largest known red diamond is the Moussaieff Red Diamond at 5.11 carats. It is a flawless, fancy red, trilliant cut stone that is breathtaking in its beauty. The stone was acquired by the Moussaieff jewelry firm for $8 million. Other famous red diamonds are the Rob Red which is a .59 carat pear-shaped stone, which has the prestige of being known as the purest and most saturated natural red diamond.

Photo credit Cape Town Diamond Museum