While most are familiar with the fiery sparkle of clear, colorless diamonds, the coveted gemstones actually occur in all colors of the rainbow.
Diamonds are the product of time and nature. It took an average of two billion years for highly compressed carbon, 90 to 500 miles underground, to form hardened crystals known as allotropes. Then, sometime within the last 100 million years or so, volcanic eruptions deep within the Earth deposited the highly structured crystals in vertical “pipes” of igneous kimberlite. Commercial miners have been extracting diamonds from kimberlite ever since the first major diamond discoveries in South Africa, in the mid-19th century.
Your diamond ring or pendant tells a great story of creation from stone to symbol of love as it dazzles and throws off light in every direction. But pass a light through a clear, colorless diamond just right and you’ll discover that it reflects all the colors of the rainbow.
Pick a color, any color, and it can probably be seen in a diamond. From the colorless to the darkest black, with variations of color in between, diamonds are hued according to the impurity of chemicals found in the Earth itself.
Colorless diamonds, for example, have no visible impurity apart from small specks of black carbon called inclusions. However, an additional natural chemical impurity and how the atoms are distributed (called “lattices”) can change the colorless into a palette of colorful options. According to the diamond industry, there are 27 different official variations of diamond colors.
What is a diamond color?
In 1953, the Gemological Institute of America (http://www.gia.com) classified the rarity of polished diamonds based on the now iconic four ‘C’s: carat (weight), how it’s cut, and its clarity. Most diamonds made into pendants, rings, bracelets, earrings, necklaces, and brooches are clear. But even colorless diamonds usually display some subtle shade of color. The more colorless, the more valuable a diamond is per carat.
To determine a diamond color, a standard grading system was developed that classified an individual polished diamond according to the shade of color ranging from D (colorless) to Z (light color). The closer to grade D, the more colorless it is and the more valuable. How is the color measured? A loose, cut diamond is exposed to ultraviolet light, which measures its “fluorescence,” or the light a diamond gives off. A yellow fluorescence is less desirable than a blue fluorescence, for example, which affects the final value of the cut diamond.
So with all that in mind, here’s a primer on diamond colors, based on information from the Diamond Manufacturers and Importers Association (http://www.dmia.net).
The fancy color diamonds
These are not actually clear or translucent, according to the diamond industry. They are classified as white diamonds, usually free of additional impurities other than pure carbon called inclusions, which determine its final value.
Curiously enough, brown diamonds are the most common color of diamonds overall. The lattices reflect the darker brown color. They don’t have the brilliance of the more pastel varieties and were mostly intended for industrial use. However, these ‘chocolate’ diamonds are gaining gaining interest beyond their industrial applications and are being set as a distinctive counterpoint to the more reflective diamonds in jewelry.
An orange diamond gets its appearance from its high concentration of isolated nitrogen. While pure orange color is very rare, those that have secondary colors such as yellow, brown or even pink are more commonly seen.
Like orange diamonds, yellow diamonds contain more of the nitrogen atom that fluorescences yellow than other diamonds. The brighter the shade, the more valuable the stone. Lighter shades of yellow that also show shades of green, yellow or even brown are more readily available.
According to diamond sites, values for diamonds in fancy colors can range from thousands of dollars a carat to nearly $50,000 a carat for the very intense color range.
The rarest diamonds
Blue and pink are among the rarest diamond colors. Such stones can sell at auction for millions of dollars per carat, depending on the vibrancy of its color.
Other diamonds that rarely appear at auction are gray, purple and green. Green diamonds, for example, are formed from natural exposure to radiation and the formation of lattices. Once found, these diamonds are usually professionally cut and retained as an investment rather than being set into jewelry.
Black diamonds have an overabundance of graphite that makes the stone rather opaque and particularly rare in a completely dark black color.
These color diamonds can range in value from $10,000 to several times that per carat depending on the vibrancy or absence of other colors when placed under UV light.
The most rare of any diamond shade is the red diamond. A pure-red diamond can auction for millions of dollars per carat. Like brown diamonds, the red diamond’s color comes from its lattice construction and not necessarily from a chemical impurity, but is very difficult to find a diamond that is pure red.
An investment that sparkles
Diamonds are considered a great addition to an investment portfolio. They hold their value, even during inflationary periods, don’t take up a lot of room, and are portable. Yet, diamonds are one of the few investments that can be appreciated aesthetically, as jewelry, rings, pendants, brooches or watch adornments. And they make a lasting personal connection when given as gifts on special occasions. That’s hard to do with stocks and bonds.
Diamonds and ethics
Diamonds are mined in different ways. The Kimberley Process Certification Scheme (KPCS) is the international standard for overseeing the import and export of diamonds to severely restrict “conflict” or “blood” diamonds from reaching the end consumer. This terminology refers to diamonds mined in a war zone and sold to finance an insurgency, an invading army’s war efforts, or a warlord’s activity. While the KPCS isn’t always successful, diamonds exported to the United States, the largest diamond market, it has strengthened the diamond trade’s efforts to keep “blood diamonds” out of the marketplace. A retailer should have the certification available to prove a diamond’s source, if asked.
From millions of years as pressurized carbon to a dazzling accessory, diamonds really are “forever.”