Engagement Series, Part 4: Natural Color Diamonds
Let's get fancy.
Today we wanted to take on a question that intrigues a lot of people: What are fancy color diamonds and how do they get that way? This article has to be a leeeeeeettle bit academic to explain this topic, so I'm going to arm you with some facts for our foray into colorful diamonds. Lucky, there are only two terms you have to know.
Crystal Lattice: This is the internal structure/substructure of the diamond. Much like how humans are made of cells or how fabric is made out of many, many threads, a diamond has microscopic structures that define how it behaves and what it looks like.
Plastic Deformation: An irreversible change in shape (aka deformation) of a solid object because of a sustained force.
Now! Onward and upward to knowledge!
Common Natural Color Diamonds
Until about 15 years ago, all black diamonds were sent away for industrial use. Clever marketing and the following fashion trends that emerged changed that--I'm sure you've seen black diamond jewelry floating around the world. These diamonds look the way they do because of microscopic black or grey inclusions of graphite or sulfides, and/or possibly microscopic fractures (don't worry, your stone will hold together just fine). What we call "salt and pepper" diamonds occur when these inclusions are spread further apart. Brown diamonds that don't have an appealing tone can be treated to look like an opaque black diamond, but natural black stones are more valuable.
When people talk about colorless diamonds they frequently call them "white diamonds," which is actually a misnomer! An true white diamond has microscopic inclusions that scatter and bend light, resulting in a milky or opalescent appearance.
Brown diamonds are the color most commonly found in nature. Much like black diamonds, these were exclusively used for industry until very recently. The color family has been divided into many different trade names, depending on the saturation of the color. Champagne, cognac, and chocolate diamonds are all the result of someone seeing the beauty in the uncommonly used stone and then marketing the heck out of it. You can generally get a brown diamond for less than any other color because they are not as vibrant than other tones. The presence of nitrogen in the stone causes the range of colors.
Falling right between a clear diamond and a black diamond, we have the grey diamond. These are found both cloudy and clear, with the cloudy variety found more readily. We love the stormy and steely tones commonly found in this family. The combination of hydrogen and nitrogen causes this color-way.
Rare Natural Color Diamonds
The green diamond is definitely one of the most interesting varieties. This rare diamond forms when it is exposed to radioactive rock during its "formative" years. Most green diamonds are very pale because the green tint is purely superficial (just a thin layer on the surface of the stone), which causes stone cutters to try to work as close to the surface as possible to preserve the color. Rarely does the radiation penetrate the entire lattice of the diamond, but it can happen. Due to its natural rarity, green diamonds are regarded with suspicion by diamond graders. The green color can be easily forced in a lab and it's nearly impossible to tell if the color is natural or not.
Technically, these babies are formed with the same elements as brown diamonds, but yellow/oranges are much harder to find. Everything from a fancy canary colored diamond to a deep, dark chocolate diamond are formed by the presence of nitrogen. An orange diamond without any trace of yellow or brown tint is the rarest color to find.
A blue diamond might be the "purest" diamond in nature. The striking color comes from the presence of boron in the crystal lattice, with a higher concentration of the element lending a more intense color. The boron present is extremely sparse (we're talking 1 part per million or less) and for the diamond to stay blue there can't be other impurities (like pesky nitrogen) present in larger quantities in the stone. Even in a flawless, colorless diamond undetectable impurities will exist in higher quantities than the miniscule boron level in a blue diamond! In the event of a blue-green diamond, a combination of boron and naturally occurring radiation caused the color.
When diamonds encounter even more pressure than normal while they were pushed through layers of earth, they end up with "graining." Graining is a deformation of the crystal structure of the diamond, creating different planes of color within the stone. Under a microscope a pink diamond will look like Zebra stripe gum, except with alternating pink and clear stripes. As of yet it's impossible to fake a pink diamond with the same grained structure, making fakes easy to spot.
Pure Violet Diamond
These are extremely rare, most people will never see one of these. This elusive color is derived from the presence of hydrogen in the stone and as well as lattice change. The extreme pressure from the earth causes the diamond to rearrange itself rather than break, causing violet, pink, and red hues.
The all time rarest color, it is speculated that this breathtaking color is caused by plastic deformation of the stone. Between 1957 and 1987 the GIA (Gemological Institute of America) has no record of a diamond report with "red" as the sole description of color--that's 30 years that no one found one! Until the Argyle Mine opened in Australia, which has a deposit of red and pink diamonds, red diamonds only hit the market a handful of times. Even now, only a handful are found a year. It's so rare in fact, that we couldn't find an image of a rough red diamond to show you!