Diamonds are some of the most precious and sought-after gemstones on the market today. These incredible gemstones have become ubiquitous with ideas of celebration, commemoration, and even memorialization. Everything from engagement and wedding rings to memorializing a loved one by converting their human ashes into a beautiful diamond has been associated with these precious gemstones. 

The value of gemstone comes down to one simple factor, and that’s scarcity. While it’s true that certain precious stones such as rubies and sapphires are technically rarer than diamonds, diamonds still find themselves as king of the gemstone market due to their popularity and diversity.

These incredibly sought-after stones are perfect for so many occasions. It may be worth asking why these stones are so sought after? What makes a diamond one of the most precious gemstones on the market and why do people love them so much? Is a diamond a rock? And if not, why?

Here is everything you need to know about diamonds from what a diamond is all the way to how they are graded and what you need to look for when purchasing one. 

What Exactly Is a Diamond?

When it comes to understanding the value and the rarity of a diamond, it helps to understand exactly what a diamond is and why it stands out from the competition when it comes to gemstones. Diamonds are very rare, unique carbon-based stones that are also one of the hardest naturally occurring substances on earth. To better understand all of this, you need to know how a diamond is formed

How Are Diamonds Formed?

Diamonds are composed completely of one substance, and that is pure carbon. This is a key characteristic of a diamond, in fact, if a stone were to have more than just carbon in its composition, it wouldn’t qualify to be a diamond at all. 

The process for carbon to be transformed into a diamond is one that takes a large amount of time and some pretty extreme conditions. Diamonds are formed in the earth’s mantel which is about one hundred miles beneath the earth’s surface. At this depth, the two most important conditions, heat, and pressure are appropriate to crystalize carbon atoms and form a diamond. 

In order to cause carbon atoms to join together in a tetrahedral form and bond in the correct lattice structure to form what we know as diamond, the temperature these atoms are exposed to needs to range upwards of 2000 degrees Fahrenheit. Not only that, but the pressure needs to be substantial as well. In the earth’s mantle, the pounds per square inch (psi) gets as high as 725,000. These incredible conditions work together to help create this precious gemstone. 

Are Diamonds an Element?

Because a diamond is composed completely of carbon atoms, it would be easy to think that these gemstones could be classified as an element. Tthat isn’t technically right. While yes, a diamond cannot be a diamond if it has any other ingredients aside from carbon, carbon itself is what could be known as an element. 

A diamond is what is referred to as an allotrope of carbon. The element, carbon, is an atom that is one of the most common and abundant atoms in existence. Most of what humanity sees around itself is known as carbon-based life. However, that doesn’t mean that substances that are composed of carbon are themselves elements. 

Instead, carbon can take on several different forms, functions, and presentations. Carbon works well with other atoms to build up life on this planet as we know it, but when a substance is completely composed of carbon it is an allotrope of carbon. This means that it is simply a different form of pure carbon or a different presentation. 

Diamond is not the only allotrope of carbon. Graphite and other allotropes of carbon are all representatives of substances that can be made up completely of carbon with their key characteristics being the carbonic bonds that make up that substance. For instance, the carbonic bonds in diamonds are different than the bonds made in graphite. That’s why they can both be composed of carbon but be massively different substances. 

So diamonds are not elements, but simply an allotrope of an element. 

Are Diamonds Rocks? What’s the Difference?

This is a very natural question as a diamond and what we would think of as a ‘rock’ hold some key similarities. The most striking similarities between a diamond and rock are that they both seemingly come from the ground and they are both hard. However, it may be surprising to find out that in fact, a diamond is not a rock. Why is this the case and what makes a rock different than a diamond?

Yes, diamonds are considered precious stones and when processed the correct way can be stunningly beautiful. These amazing gemstones can be fitted to everything from engagement rings to bracelets all the way to royal crowns, but this isn’t what makes them different from what we call a ‘rock’. The actual reason why a diamond is not considered a rock is because of its composition. 

A rock, by definition, is a substance that is made up of two or more minerals. Rocks are what we commonly see in nature and while they are made up of minerals, they are not specific. This means that a rock can have any number of mineral compositions and varieties. What’s more, is that rocks can be of a variety of sizes. All the way from a pebble to literally being large enough to climb on top of, rocks have a vast amount of variety. 

What’s more is that rocks are not considered to be in either of the categories that gemstones find themselves in, precious or semi-precious.

What Is a Gemstone?

A diamond finds itself in the category of being a gemstone. This is uniquely different from a rock as a gemstone is typically composed of one mineral that has crystalized. The world of the gemstone also finds a wide array of variation within it. There are certain crystallized minerals that qualify as gemstones that are placed in the semi-precious category while others as placed in the precious category.

The most important distinction between precious and semi-precious gemstones is simply their abundance. A semi-precious stone is more commonly found than a precious. Diamonds, rubies, and sapphires are all examples of precious gemstones that are rare and very valuable. 

These gemstones are not just mined and collected because they are rare, but also because they can be processed into stunningly beautiful works of art. A gemstone has the unique quality of being able to be processed through cutting and polishing, into a stone that has a certain aesthetic and sought-after quality. Most rocks are not considered beautiful and are not processed in this way. 

How Are Diamonds Assessed?

Now that you know how a diamond is different from what is commonly known as a ‘rock’, here is what you need to know about assessing a diamond’s worth

When a diamond has been collected and processed, its quality and worth are assessed by what is known as the four Cs. This universal standard of assessing a diamond’s quality is something that all jewelers use and is a good tool to be aware of when looking for a diamond to purchase.

Just because a diamond is considered to be rare and precious, doesn’t mean that all diamonds are the same or valued equally. The process of making diamonds takes a lot of time and very specific amounts of pressure and heat. This lends itself to the reason for why a diamond is considered precious and rare, however, even amongst the diamonds that do exist there are different levels of perfection and quality. 

The four Cs look at a diamond’s clarity, color, cut, and carat (or mass). 

When a diamond is assessed for clarity, the degree of internal blemishes (called inclusions) and external blemishes are assessed. These blemishes and inclusions would have been created during its development and most notably hinder light from reflecting or passing through a diamond. The fewer inclusions and blemishes a diamond has the higher its value. 

A diamond’s color is also an important factor, as the purity of a diamond is related to its absence of color. A diamond with the greatest absence of color is considered to be of higher value. Lastly, the cut and carat of a diamond refer to the quality of cut polish a diamond has along with its size. 

Since each diamond is unique, each diamond has a unique cut that will bring out the most shimmer and sparkle from the stone. The right cut that suits a particular stone will increase its value. 

Lastly, a carat is a universally used measurement of 0.200 grams to assess a gemstone’s mass.


Diamond | Bris.

4 Cs | GIA

How Do Diamonds Form? | Geology 

6.1 What Is A Rock? | USASK