Have you ever wondered what a sparkly diamond looked like before it was cut and polished? Known as raw diamonds, these gemstones are a paradox: a rough exterior, yet holding the potential for brilliance once polished. Explore the science and mystery behind these unique gems with a journey to the Earth’s mantle.
What are Raw Diamonds?
The term "raw diamond," also known as "rough diamond," refers to a diamond in its unrefined state. Unlike the polished gems that adorn dazzling jewelry, a raw diamond exists in its natural form and requires the skilled hands of a diamond cutter to unlock its true beauty.
How Are Diamonds Created?
While your inner child may want to believe that diamonds are made by Superman crushing a piece of coal between the palms of his hands, your inner child would be incorrect. Diamonds aren’t made from coal at all. While coal contains other substances like hydrogen, nitrogen, oxygen, sulfur, arsenic, selenium and mercury (and even decayed plants, fungi, bacteria and moisture), diamonds are essentially pure carbon that has formed into a crystalline structure.
Carbon requires extreme pressure and heat to become a diamond. These conditions can typically be found in the Earth’s mantle (the largest part of our planet between the core and the crust), about 125 miles below the surface. Fun fact: Diamonds form in the Earth’s mantle, but rubies, sapphires and emeralds form in the Earth’s crust, closer to the Earth’s surface.
Diamonds also require cool air and quick pressure-reduction, or graphite will form instead. Volcanic eruptions create these ideal diamond-making conditions when they carry deposits from the Earth’s mantle. There are three different types of diamond deposits that create three different types of diamond formations.
- Kimberlite: The main form of diamond deposits, kimberlites, are formed when magma, minerals, rocks and diamonds mix and create cone-shaped pipes. These champagne flute-shaped deposits are forced to the surface by volcanic activity.
- Lamproite: These martini glass-shaped diamond deposits are formed like kimberlites except boiling water and volatile compounds in magma corrode the overlaying rock. This results in a broader cone, with diamond deposits at the surface.
- Placer Deposits: Placer deposits were formed millions of years ago when diamonds fell out of their kimberlite parent and were transported by seasonal flooding, rivers or streams and ultimately came to rest in river sediment or sand.
How to Identify Raw Diamonds
If you’ve ever stumbled across a raw diamond, or you’re looking to purchase one and want to ensure you’re not being swindled, here are some things you’ll want to evaluate:
- Shape: Raw diamonds have rough, unpolished exteriors and often retain their original crystalline structure, such as an octahedron (eight equal triangular sides, looking like two pyramids connected at the base).
- Clarity/Imperfections: Most raw diamonds will have visible inclusions, or tiny flaws or imperfections trapped inside the stone. These inclusions may be other minerals, crystals or even empty spaces. Gems with non-uniform distribution of inclusions are more likely to be mined but be careful.
- Cleavage: Most raw diamonds have a specific crystal structure that creates preferential directions for breaking, called cleavage planes. These planes are typically octahedral, meaning they resemble eight-sided shapes.
- Color: Natural diamonds can be colorless, yellow, brown and even rare hues like blue or green. This vast range makes it difficult to rule out authenticity based solely on color. (Color is one of the 4 Cs of a Diamond - the system used to grade diamonds).
- Unusual Colors: If a raw diamond exhibits an extremely vibrant or unnatural color, it might raise a red flag. However, mined diamonds can change colors during formation, resulting in some truly rare, uniquely colored diamonds.
- Color Distribution: Natural diamonds often have uneven color distribution. For instance, a yellow diamond might have some colorless areas or show a concentration of color in certain zones.
- Hardness: Diamonds are known for their hardness, which makes them extremely resistant to scratching. A “scratch test” can be performed by taking a piece of corundum (ruby or sapphire) and scratching it against the suspected diamond. If the rock believed to be an uncut raw diamond doesn’t scratch, it is likely authentic.
- Mineral Testing Kit: While it might be easier to take your diamond-in-question to an expert, you can also give an at-home mineral testing kit a try first. There are plenty of mineral testing kit options available through online vendors.
What Does the Common Phrase “A Diamond in the Rough” Mean?
Diamond analogies have been used for hundreds of years. The first known mention of “rough diamonds” in writing was John Fletcher’s 1624 play, A Wife for a Month, in which a woman is said to be “very honest” and “as hard to cut as a rough diamond.”
However, the more commonly known phrase, “diamond in the rough,” (used to describe an individual who has exceptional qualities or potential, but is a bit unpolished), was first seen in Town and Country Magazine’s December 1776 issue: “Mrs. Robinson has made her appearance at Drury-Lane theater, in the character of Juliet, and was received with applause. If we may be allowed a comparison, she appears like a diamond in the rough; and, we think, when she has received the polish of time and stage knowledge, she will be a considerable ornament to the stage.”
Raw Diamonds in Jewelry
Even though cut and finished diamonds are certainly more common and more popular, raw diamonds also have their place in jewelry. Raw diamonds can be used in jewelry just as a finished diamond would be, finding their way into engagement rings, earrings, necklaces, bracelets and more, with increased popularity in recent years. Their natural, unique form makes raw diamonds a perfect option for those looking to express their personal style, especially those who prefer more natural-looking styles. A raw, uncut diamond may also be a more affordable option (depending on the stone) making it a perfect choice for those buying diamond jewelry on a budget.
A Few Remaining Questions About Raw Diamonds
Now that you know the basics of where, from what and how diamonds are formed, it’s time to expand your raw diamond knowledge even further with a round of bonus questions!
- Can Polished Diamonds Be Found in Nature? While the phrase "diamonds in the rough'' refers to unpolished stones, some diamonds are actually made smooth by natural processes. Many years of erosion can wear away the rough exterior of a raw diamond, revealing some of its natural sparkle without human intervention.
Can Diamonds Only Form on Earth? It’s true that diamonds form in the Earth’s mantle. However, diamonds aren't just found deep within the Earth. Collisions in space between stars can create incredibly strong diamonds. The intense pressure and heat during these events can compress carbon-rich materials into diamonds.
One interstellar diamond, the Enigma, dates from 2.6 to 3.8 billion years ago and its value is estimated between $5 million and $7 million. The stone contains osbornite, a mineral exclusively found in meteors, confirming it didn’t come from Earth. Small diamonds can also be formed by asteroid impacts with Earth, as the pressure, heat and material make-up create the perfect environment for diamond creation.
Do Raw Diamonds Come in All Sizes? Most diamonds are quite small, but the Cullinan Diamond was anything but. The largest raw diamond ever found, weighing in at an astounding 3,106 metric carats, the Cullinan Diamond was discovered in 1905, near Pretoria in modern-day South Africa. Named for the chairman of the mining company that discovered the diamond, it was celebrated for its size, blue-white color and exceptional clarity.
The Transvaal Colony government gifted the Cullinan Diamond to King Edward VII of England as a birthday present. It was then cut into nine large stones, including the famed "Great Star of Africa" (530 carats) and "Second Star of Africa," (105.6 carats) which now belong to the British crown jewel collection.
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