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Types of Diamonds

By Frank

Highly experienced diamond polisher who loves to share his knowledge with you. Continues to stun his colleagues with interesting - or simply bizarre - facts about diamonds and gems.

February 28, 2020

Sometimes, we receive questions from people who are (almost) as fanatic about diamonds as we are. For some questions I need to dig deep into the material. However, some of my “diamond bibles” don’t make it easier to understand at all. Some literature was written ages ago. While other is too theoretic to create a clear image. A third option is when there are too many explanations. In that case, there is more than one way to interpret a question. A question that covers all three of the above-mentioned struggles is: “Which types of diamonds are there?”. Now for me, there lies a beautiful task to explain it in a clear and easy way.

3 ways to interpret the question

When people ask me “what types of diamonds there are” they usually mean one of these three “types”.

  1. Natural diamonds vs. non-natural diamonds
  2. Colorless diamonds vs. colored diamonds
  3. Type I vs. Type II diamonds

The first question is about the origin of the diamonds. How they are made and what the difference between these stones is. The second question is about the color and the chemical composition of a diamond to radiate a certain color. The third question is the most theoretic one. This refers to the presence or absence of nitrogen impurities. I will get back to that shortly. Let’s start with answering question 1 first.

Types of diamonds in terms of natural versus non-natural

To explain this correctly, we need to have a clear understanding of the definition of a natural diamond. Once we have this, we can examine which other types of diamonds there are. Then we can tell whether these are in fact natural or non-natural.

What is a natural diamond?

Natural diamonds form under high temperature and high pressure, hundreds of kilometers beneath the surface of the earth. These gems consist of carbon atoms. The atoms are bonded the same way in all directions creating a colorless “rock” with an unbelievable hardness. These rocks are natural diamonds. The diamonds get to the surface with volcano eruptions or are dug up in diamond mines. Most of the natural diamonds are not very high quality. They get used in industrial equipment. But a few percentages of the diamonds are of high quality. These are the stones you’ll find in luxurious jewelry.

natural diamond in black rocks

What is a non-natural diamond?

Now we know what a natural diamond is, it is quite easy to explain what a non-natural diamond is. Basically every diamond that is created in a different way than a natural diamond, means it is a non-natural diamond. The term we have for non-natural diamonds is ‘synthetic diamonds’. These diamonds are created by mankind in a lab. That’s why we also call them ‘man-made diamonds’ or ‘lab-grown diamonds’.

Creation of synthetic diamonds

In the lab, scientists place the element carbon under high-pressure and high-temperature. This so-called HPHT process creates a diamond crystal. Another way to create a synthetic diamond is by chemical vapor deposition. In this process, a scientist takes a small piece of a natural diamond. This small piece is what we call a ‘seed’ because this will form the base for a new diamond. The seed gets placed in a chamber. In this chamber, the seed grows layer by layer. Many people call synthetic diamonds ‘fake diamonds’ because they are not natural. But that is not correct. After all, the diamond are created in a lab. But the way the atoms are bonded is the same way as they are in a natural diamond.

white and colored diamonds

Types of diamonds in terms of colorless versus colored

There are various ways to look at types of diamonds in terms of colors. There are natural colored diamonds and artificial colored or “enhanced” diamonds. First I will tell you about the different colors and how they occur. A diamond can be almost every color imaginable. Most diamonds are a variety of colorless ones. But there are also fancy colored diamonds. These stones have a bright color, such as blue, pink, yellow, orange, purple and green.

Colorless diamonds

Apart from the ‘fancy colored’ ones, colorless diamonds are the most precious of all. Because it is quite difficult to describe a colorless diamond, we often refer to these stones as ‘white diamonds’. Note that this doesn’t mean these diamonds are actually white. We just call them that to explain the category of colorless diamonds. By category, I mean the color scale we use to describe colorless (or white) diamonds:

diamond colors explained with old and current names

As you can see in the scale above, a ‘white’ diamond can range from D all the way down to Z. D-colored diamonds are perfectly colorless. While K-Z have a noticeable yellowish hue over them. That is because of the carbon. If that is polluted (for example with nitrogen), the diamond gets a yellowish or light brown color. The more a diamond is affected, the more yellowish it will be. While color is not the only factor to determine a diamond’s value, it is one of the four that do. In general, you can say that the more colorless a diamond is, the more valuable it is.

Fancy colored diamonds

On the color scale, you see that the last stone on the list (P-Z) is almost yellow. We call this one ‘yellowish’. But there are also bright yellow diamonds. We call these ones ‘fancy yellow’. The same goes for other types of diamonds with a color. Fancy colored diamonds come in almost any color imaginable. There is red, green, purple and orange, which are the rarest of all colored diamonds. They are followed by pink and blue, which are also very rare. And of course, the yellow I just mentioned and brown. These two are the most common fancy colors. However, fancy yellow diamonds still represent a very small portion of the overall diamond productions. Therefore, fancy equals rare. Black, gray and fancy white diamonds are also fancies. Fancy white diamonds have an opalescent look. Black and grey are quite self-explanatory.

colored diamonds on black background

The intensity of colored diamonds

When you compare fancy yellow diamonds to yellowish diamonds, you notice that fancy yellows are much brighter. Therefore, you might think that fancy means ‘color intense’. However, that is not the case. Many natural fancy colored diamonds are not very intense at all. The intensity of a natural colored diamond can vary from faint or very light to deep or rich. The deeper the color, the more valuable the diamond is.

It is also possible to enhance a diamond’s color. With high temperatures or x-ray radiations, it is possible to make the present color of the diamond stand out more. It is even possible to transfer white diamonds into colored diamonds and vice versa. There are several (shady) companies that sell these so-called “treated” stones. They claim the color is forever – just like the diamond. However, more and more research shows that these enhanced diamonds lose their color over time. Some people care about this a lot while others don’t really mind the color may fade over time. Nevertheless, it is very important you’re informed about this before you make a purchase. A treated diamond can always lose its color and go back to its original color.

bunch of fancy cellow diamonds

Types of diamonds in terms of Type I versus Type II

The third and last one of this list of types of diamonds is also the most difficult one to explain. When we talk about Type I and Type  II diamonds, we talk about them on an atomic level, literally. Let’s start from the beginning.

Basically the main difference between Type I diamonds and Type II diamond is this:

  • Type I diamonds are diamonds with nitrogen impurities
  • Type II diamonds are diamonds without nitrogen impurities

What are Type I diamonds

Type I diamonds are diamonds with nitrogen impurities. Nitrogen in a diamond’s (atomic) structure causes the diamond to become yellowish. Remember the color scale from earlier? That’s mostly because of (traces of) nitrogen in the diamond’s structure. As you can imagine: more nitrogen means more yellowish. Less nitrogen means less yellowish.

What are Type II diamonds

Type II diamonds are diamonds without nitrogen impurities. At least not enough nitrogen to detect. This means the diamond can have no (noticeable) impurities at all, or boron impurities. Boron can give a diamond a blueish color.

diamond structure

Ready to go deeper about types of diamonds?

To really comprehend what happens to the diamond, we have to look at the construction of atoms in the lattice of the diamond. The lattice is the way in which the atoms are connected.

One kind of atom in the lattice

A pure diamond is made from only one element: carbon. When we look at the structure of the diamond in terms a carbon atom (c) it looks like this:

perfect diamond structure

Every C is connected to another C by two, three or four connections. Together, these connections of carbon create one carbon atom. Because this diamond has no impurities, we now know this is a Type II diamond. After all, there is no nitrogen in it. But we refer to this as a Type IIa diamond. That is because there is also a Type IIb diamond. That is when another element than nitrogen slipped into the structure of the lattice.

Another kind of atom in the lattice: Type IIb

Boron can take the place of a carbon atom. When this happens, the structure of the diamond looks like this:

boron in diamond lattice

As you can see, a few boron atoms slipped into the structure of the diamond. This gives the diamond a blueish color.

So what about Type I diamonds

Type I diamonds are the most common type of diamonds. That is why we call them Type I. Type I diamonds always have some nitrogen atoms in them. The nitrogen gives them that yellowish hue. The nitrogen can be singled out, just like the boron:

isolated nitrogen types of diamonds
Isolated nitrogen impurities (Type Ib)

Type Ia diamonds

We call diamonds with isolated nitrogen impurities Type Ib diamonds. That’s because most diamonds are Type Ia diamonds. These Type I diamonds have nitrogen atoms that are “grouped” together:

Type IaA and Type IaB diamond structure

Type IaA and Type IaB

The grouping of nitrogen atoms can be in two different ways. In Type IaA Diamonds, two or more nitrogen atoms are directly linked to each other. Whether this is once N-N or twice, that doesn’t matter. Another way nitrogen atoms can be grouped is when there is a vacancy. This means there is an atom missing in the structure of the diamond. This happens sometimes. In a Type IIa diamond, this has no consequences as there are carbon atoms all around the empty spot. But in a Type Ia diamond, it is possible that atoms of nitrogen surround the vacancy. In this case, the nitrogen atoms are connected and grouped indirectly. These diamonds are the ones we call Type IaB diamonds.

A combination of Type I and Type II diamonds?

Now it’s time to see how it all comes together. Is it possible to have a diamond that consists of both Type I and Type II? It’s not possible for natural diamonds. The gems that come from Mother Nature are always either Type I or Type II.

two blueish diamonds

However, remember the non-natural diamonds I mentioned earlier. Usually, they are also Type I or a Type II diamond. It is (in theory) possible to create a combination of Type I and Type II. For example with the ones created with chemical vapor deposition where you start with a diamond seed. The seed grows into a (bigger) diamond because of the new layers it gets. It is possible to create a Type I or Type II layer and wrap this around the diamond seed. However, this is not something that happens in reality. If you want to go even deeper into the types of diamonds, I recommend this article about the Type Classification System of Diamonds. But be aware, it’s a tough one!

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