The classic image of the cut diamond is that of a scintillating cut stone with a beautiful blue colour, thanks in large part to the famous Hope Diamond. Sometimes, diamonds are presented in popular media as being “white,” or clear. A chemically pure diamond would in fact be clear and colorless, but few naturally occurring gem-sized diamonds can approach this. The overwhelming majority have chemical defects, or inclusions, and structural imperfections, which result in a wide range of beautiful and dazzling colours.
Most mined diamonds are either a pale yellow or a pale brown, which is referred to as the “normal colour range.” A brighter, more intense hue is considered “fancy.” A fancy diamond’s colour reflects its rarity, thereby having a substantial impact on the value of a cut and polished stone. With normal diamonds, the less colour there is, the more valuable a stone will be relative to others of its hue. This is because, when it has been finished, a diamond with less colour will appear brighter, by virtue of its facets reflecting a greater amount of light. It will appear more like a pure white diamond.
Naturally occurring diamonds are far more valuable than diamonds which were created in a laboratory. These natural, gem-grade stones are recognized as occurring in the following colours:
Diamond colour is graded on an internationally recognized scale ranging from D to Z, which is used by the most prestigious and widely recognized geological and gemmological laboratories. A D-grade stone is completely clear, or “white,” with the colour representing the appearance of the stone at its most reflective. A Z-grade stone is a pale brown or yellow, one of the most common diamonds.
This grading system is an important point of consideration to take into account with regard to investment diamonds. The more valuable a diamond is, the more it is likely to appreciate in value, making more precious stones a better choice for investing in. A smaller number of diamonds is also easier to conceal, to transport, and to identify.
Steel gray diamonds are known by a variety of names, including charcoal, slate, and pigeon gray diamonds. They are sometimes referred to as “silver diamonds,” and result from the inclusion of either hydrogen or boron in the crystal lattice of the stone. They offer a variety of subtle differences in hue, but relatively few levels of intensity compared to certain other colours. The famous Hope Diamond has been evaluated as having steel gray as a secondary colour, as many other famous diamonds do. Historically not a popular hue, steel gray diamonds have been gaining popularity in recent decades, with the rate at which their value is increasing being among the most impressive.
A white diamond is a clear stone which reflects the broadest spectrum of light, thus appearing to be a brilliant white colour under ideal viewing conditions. Most white diamonds are not pure, with the most common inclusions resulting in pale yellow or brown tints. These impurities reduce the value of the diamond, and are a part of what the stone’s cut will be designed to minimize.
Fancy blue diamonds are among the rarest of diamonds, and are consequently among the most valuable. Historically, most of the famous stones in existence were classified as blue diamonds, and most still have blue recognized as their primary colour. Blue diamonds represent a significant investment, but are one of the best choices for investment diamonds due to their individual value. Fewer than one-tenth of one percent of all fancy grade diamonds are blue diamonds.
While one of the more common diamond colours overall, and among the most common of fancy diamonds, fancy grade yellow diamonds have a relatively high value when held against their rarity. They have been a popular choice in gold and silver jewelry for many years, and more recently they have become well-established as a favorite in engagement rings for their warm and sunny aspect.
Famously referenced as “fire diamonds” in the 1882 volume “The Great Diamonds of the World,” an orange tint isn’t the rarest of hues overall, but a pure orange stone is one of the rarest of grades. They are extremely desirable, they cause a sensation on the auction block, and they are hotly sought after by collectors. Their already considerable value is one of the fastest to appreciate, making them a solid investment option.
While the frequency of certain colours is up for debate, the rarity of the red diamond is beyond question. Red diamonds are extraordinarily rare, and are so valuable that the purest of them are usually beyond the reach of the celebrity lifestyle. There aren’t more than five or six red diamonds of significant purity and more than one fifth of a carat in weight available on the market at any given time, anywhere in the world.
Green diamonds are classified into eight different intensities, ranging from a soft minty hue to a deep, rich jade color. Among fancy grade diamonds, green diamonds are among the rarest, as well as being individually unique. Their colour results from exposure to radioactivity, requiring extremely uncommon conditions in the natural world.
Inclusive of purple diamonds, the pink diamond colour is another rarity, resulting in highly sought-after stones. Like red diamonds, pink diamonds are something of a mystery: their hue is thought to be the result of changes in the diamond’s electron structure as it travels toward the surface of the Earth. The colour is indicative of certain unusual conductive qualities. More than 90% of all pink diamonds in circulation come from a single mine in northwestern Australia.
Brown diamonds appear darker due to structural defects in the diamond’s crystal lattice, which cause it to absorb wavelengths of light that would otherwise reflect back in dazzling display. The color may also be caused by nitrogen inclusions. Brown diamonds are the most common diamonds, and are found in mines throughout Africa, Australia, and Siberia.
Black diamonds form due to unusually large inclusions of graphite and iron, resulting in their characteristic dark appearance. This results in a mostly or entirely opaque stone, which lacks the brilliant and dazzling display of other types of diamond. They cleave somewhat unpredictably due to their inclusions, and fracture more readily than other diamonds. Few black diamonds are rated as gem-quality as a result, although those that are may actually be heat- and pressure-treated to ensure a more uniform colour.