Many people who are aware of the existence of colored diamonds, often mistakenly believe them to be treated or synthetically colored stones.
However, colored diamonds occur naturally in all colors of the rainbow, ranging from vibrant red, pink and orange, to brilliant blue, green, violet, and muted yellow, brown, gray – and even black.
Colored diamonds are extremely rare, and much more so than clear or colorless diamonds. In fact, the formation process of colored diamonds occurs so rarely in nature, that less than 1 carat of colored diamond is found for every 10,000 carats of clear diamonds mined. Given their rarity, colored diamonds are also considered significantly more valuable, and demand is considerably higher.
However, not all colored diamonds are equally rare. For example, black, brown and yellow diamonds occur much more frequently than green or blue diamonds. For comparison, only 2 to 4 major blue diamonds are released to the market every year, and only 50 Fancy Vivid blue diamonds have been sold at auctions since 1999.
In comparison, red diamonds, the rarest of all the colored diamonds, occur so infrequently that even experienced jewelers never see pure, or Fancy Vivid red diamonds in their lifetime. Few colors of fancy colored diamonds come in only a single color intensity, and red diamonds are one of these rare stones.
Red diamonds occur in only the Fancy intensity, and only around twenty to thirty true red diamonds are known to exist in the world. Most of these are less than half a carat in size, and valued at amongst the most expensive diamonds in price per carat.
The formation process of colored diamonds is largely similar to that of white diamonds: all diamonds are composed of carbon atoms that are transformed by extremely high temperatures (around 1300° to 2000° C) and tremendous pressure (70 ton/cm²) into a crystalline structure.
These transformations occurred in the Earth’s mantle 150 kilometers below the surface, as a result of geological processes that lasted millions of years between 550 million to 4 billion years ago. As they are composed of the same element and transformed by the same process, colored and colorless diamonds have the same material properties, scoring 10 on a Mohs scale, which makes them the hardest natural material on earth.
Despite being composed of the same element, being acted upon by the same physical processes, and having formed in the same time span and geological region, there is one small but key difference between the creation of colored and colorless diamonds.
This singular difference involves a chemical interaction with foreign particulates that integrate into the diamond’s carbon structure during the crystallization process. This chemical process can include interactions with other elements such as boron, nitrogen, as the result of uncommonly high temperatures or pressures (as is the case with red or pink diamonds), due to radiation (such as with green diamonds) or even due to a higher than usual concentration of inclusions of carbon, the native element (as is the case with black diamonds).
Depending on how the chemical process of diamond formation is affected, and by which abnormal factors, the result is an extremely rare and exceptionally beautiful natural colored diamond.
Diamonds come in 27 base colors, listed in the color wheel above. However, with the varying levels of intensities and modifying hues, this results in over 200 color combinations.
In addition, the various clarity, cut, and shapes of colored diamonds mean that your invaluable colored diamond is truly one of a kind.
The least expensive of the colored diamond colors include brown, gray and yellow – the most commonly occurring of the colored diamonds. Although these colored stones are more rare than white diamonds, they typically cost less than white diamonds of a comparable quality and carat due to generally lower levels of demand.
However, the relatively lower cost is not applicable for stones with stronger intensities such as intense, vivid or fancy vivid yellow, or for a diamond with a modifying color that is more valuable, such as a blue gray diamond.
The mid-range priced level of diamonds include stones with lower saturations due to the presence of secondary colors.
Price ranges for this group of diamonds vary greatly depending on the strength and tone of the secondary color, however typically diamonds in this category are generally more expensive than white diamonds.
Mid range colored diamonds often include orange diamonds, which commonly come with strong modifying hues.
The mid range diamonds also includes Intense yellow or “canary” diamonds, which are more expensive than the typically “affordable” yellow diamonds.
The most expensive, and rarest, colored diamonds are significantly more expensive than white diamonds, with a value that rises exponentially the higher the carat and color intensity.
These includes pink, purple, green, blue, violet and pure or “pumpkin” orange diamonds. Even the base valuations of price per carat usually start in the tens or thousands of dollars. Loose diamonds of these colors are typically sold through auctions for bids that are easily in the millions of dollars. Given the rarity and demand for these colors, they also tend to make secure investments that are likely to see exceptional returns.
A few high profile purchases of the world’s rarest and most expensive colored diamonds include:
Despite the stunningly high prices of rare colored diamonds, there is one diamond color so rare that only 20-30 have been known to ever exist in recorded history; and even most of these are extremely small: half carat or smaller.
Red diamonds are the most rare and most expensive of all the colored diamonds, and come only in a single intensity: Fancy.
They are so rare, and there is such a small set of pure red diamonds on the market historically, that it is very difficult to determine prices for them. Even when red diamonds appear with a purple modifying color (the most commonly found secondary hue in red diamonds), prices vary dramatically based on the percentage saturation of red in the stone. However, typically, a 0.20ct purplish red can cost about $300,000 per carat and 0.40ct about $500,000.
The red color in diamonds is so rare that even if the red color appears in a diamond at an extremely low saturation, as a modifying secondary color, the price of that diamond will rise exponentially. Thus, while a brown diamond costs only about $2,400 per carat, a reddish brown diamond can cost the astonishing sum of over $30,000 per carat – over 12 times as much due to the effect of the red color! No other color has such a drastic effect when it appears as a modifier.
The most known red diamond is the Mousaieff Red – a 5.11ct Pure Red diamond that was purchased for over $ 1.6 million per carat. Recently, at the 2013 Argyle Pink Diamond Tender, a 1.56 carat red diamond known as the Argyle Phoenix, was sold for over $1.25 million per carat.
The intensity color grading of a diamond is based on a combination of saturation and tone, and represents the color’s strength and vibrancy. The color grading of the GIA, is divided into 9 color intensities: faint, very light, light, fancy light, fancy, fancy intense, fancy vivid, fancy dark, and fancy deep.
This is the primary factor that affects the cost and demand of a diamond – the higher the intensity of the color, the rarer, and more valuable the diamond is.
While the intensity of the color, is the primary factor that influences the pricing of diamond, the other 3 C’s – Carat, Clarity and Cut – are also important considerations.
Carat – represents a diamond’s weight (not size). As a rule, the more carats, the higher the price per carat, as well as the higher than a price overall.
Clarity – indicates a stone’s structural perfection. While flaws are not usually visible to the human eye, the clarity scales set by gemological institutes such as the GIA, specify the diamonds’ level of internal clarity when magnified 10,000 times.
The clarity rating is represented in a scale that includes 9 grades divided into 6 groups:
FL – Flawless: No inclusions or blemishes are visible even at 10x magnification.
IF – Internally Flawless: No inclusions, only blemishes visible at 10x magnification.
VVS1, VVS2 – Very, Very Slightly Included: Inclusions slightly visible at 10x magnification.
VS1, VS2 – Very Slightly Included: Minor inclusions clearly visible under 10x magnification.
SI1, SI2 – Slightly Included: Minor and major inclusions visible at 10x magnification.
I1, I2, I3 Included: Inclusions are obvious at 10x magnification and visibly affect transparency and brilliance.
Cut – refers to the way the diamond is polished to best flatter its natural qualities, maximize its color, augment its sparkle and make it look larger than its actual carat weight.
Colored diamonds, are generally cut into pear, radiant, cushion, or other unconventional shapes as such fancy shapes, which reflect less white light, work to enhance the intensity of the color.
It is possible to find colored diamonds in rounds, princess and emerald cuts. However, as it is very difficult to cut colored diamonds into these shapes without losing color, these shapes are usually rare, and extremely valuable.
Synthetic diamonds are created artificially from carbon. This process barely requires three weeks, compared to billions of years for natural diamonds. Only laboratories possessing leading-edge technology are able to detect these diamonds, which have exactly the same physical and chemical properties as natural diamonds.
The surest way to determine the authenticity of a diamond is to see its certification. A certification is a report from a reputed independent laboratory such as the G.I.A. (Gemological Institute of America), that testifies to the stone’s authenticity, origin, and unique features.
A variety of different techniques are currently used to produce synthetic diamonds
CVD (chemical vapor deposition): this technique was developed in the late 1960’s and involves the propulsion of CO2 into plasma. The diamonds created with that process are low nitrogen type IIa crystals, and can be colorless, brown, faint pink, blue or black.
HPHT (high pressure high temperature): The most widely adopted technique, HPHT subjects carbon atoms to very high temperatures and pressures, re-creating the geological conditions in which diamonds crystallize.
HPHT diamonds are extremely similar to the “real thing” and one of the few ways to detect differences is by using special equipment to reveal growth lines in the crystal.
Another way to recognize a synthetic diamond is that it has characteristic impurities quite different from those occurring in natural colored diamonds. Even the most perfect natural color diamonds have some minor blemishes invisible to the eye. These are the signature of the natural creation process, and part of the unique character of each diamond.
A third method exists: the DND (Detonation Nanodiamond) It consists of using a detonation to make diamonds. However, as this recent technique only allows to produce tiny particles of diamond. Therefore, it is only used for industrial and medical purposes.
Treating natural diamonds does not mean the diamonds are synthetic as opposed to the above where the diamond is actually created. Instead a colorless diamond is taken and ‘treated’ to change its properties and lend it a particular hue.
However, while it is easy to find treated or synthetic diamonds on the market, a natural colored diamond is truly rare – and increasingly in demand.
With colored diamonds becoming more popular both as fashion accessories and as investment options, it’s no surprise that values are increasing exponentially.
