The Science of Colored Diamonds
We often think of natural diamonds as the scintillating colorless or white gems that humans have cherished for thousands of years. Formed deep within the Earth under extreme heat and pressure, these treasures only develop when carbon atoms bond together in a crystal lattice structure. But what many forget is that during a diamond’s formation, certain variables, like the internal trapping of non-carbon atoms or changes in pressure, can alter the stone. This results in diamonds of nearly every color in the rainbow, better known as “fancy colored diamonds.” This natural phenomenon is one of the rarest and most beautiful things we see in nature.
Yellow Diamonds: More Abundant, but Striking Nonetheless
The most common of all non-carbon atoms found in diamonds is nitrogen. Most diamonds we see contain some nitrogen, but only enough to give yellow hints to otherwise colorless diamonds. In fact, the most common color grading scale for diamonds ranges from D to Z; D is completely colorless while Z contains enough nitrogen in the right place to give the diamond visible color.
When enough nitrogen gets properly trapped inside of a diamond’s forming crystal structure, the diamond can transcend its Z classification. Instead, it can be identified as a“fancy yellow diamond”that presents itself in an unlimited range of beautiful yellow and brown colors. While still extremely rare, fancy yellows are abundant in comparison to other fancy colored diamonds, making their prices comparatively affordable. Buying a fancy yellow diamond can be a perfect foray into the fancy colored diamond world.
Pink Diamonds: The Most Desirable—and Ultra-Rare
Without a doubt, the most desirable natural diamond color is pink. Not only are the full range of very light pink to red diamond hues considered amongst the most beautiful on Earth, but they are some of the rarest miracles of nature we are likely to see. Unlike other natural diamonds that boast a beautiful color, pink diamonds get their color via a phenomenon called plastic deformation. This requires extreme pressure to compress the diamond’s crystal structure in such a way that causes them to reflect red light. The more extreme the plastic deformation is, the more saturated the color of the diamond. This makes it more difficult to achieve a high clarity grade and carat size.
The majority of pink diamonds are found in one place on Earth, the Argyle mine in remote north western Australia; its closing at the end of 2020 means that pink diamonds are growing rarer and more valuable by the day.
Green Diamonds: A Most Intriguing Fancy Diamond Color
Green diamonds form in perhaps the most interesting way compared to other colored diamonds. Their color is a result of Earth’s naturally decaying radioactive materials emitting penetrating radiation that knocks electrons or carbon atoms out of their crystal lattice position, causing the stone to reflect green light. Green diamonds are also the only fancy color diamond to achieve their color after they have made the long trip close to the Earth’s surface.
Blue Diamonds: The Rarest and Most Intriguing of Diamond Colors
Blue diamonds are some of science’s rarest and most intriguing diamonds as they only form when the natural element of boron gets trapped inside their crystal structure. Boron absorbs yellow light and thus reflects blue light; subtle differences in the concentration and positioning of these boron atoms result in different hues and shades of blue.
Thanks to research by GIA scientists, we now know that the origin of natural blue diamonds is far deeper (up to four times!) inside the Earth than that of most other diamonds. We are lucky enough to find these beauties due to a process called subduction. Subduction is when the Earth’s tectonic plates act like a conveyor belt, moving up and down over hundreds of millions of years and bringing the blue diamonds with them.
The True Rainbow of Fancy Colored Diamonds
Just as you mix yellow and red paint to make orange, natural phenomena that cause color in diamonds can exist on their own or in combination, forming nearly any color in the rainbow. Though not common, It is possible if a diamond with a plastic deformation (like, say, a pink diamond) also has enough nitrogen (like a yellow diamond), you get an orange diamond. This serves as further proof that no two natural diamonds are ever exactly alike.
While all natural color diamonds are beautiful in their own ways, what makes them extraordinary is their extreme rarity. All of the world’s diamonds one carat and above recovered within one year would only fill one exercise ball. Natural fancy colored diamonds comprised only 0.4% of all graded diamonds in the last 20 years. This means that the amount of pink diamonds recovered in a year would only fill a champagne flute. As the Natural Color Diamond Association reports, only one natural blue diamond can be found on the market for every 100 Picasso paintings up at auction. These diamonds are indeed a remarkable gift of mother nature.
Source: The Natural Diamonds Council