What are Colored Diamonds: How Do They Differ from Colourless Diamonds

 For a long time, coloured diamonds remained a mystery in the world of gemstones and gemstone jewellery. Long considered the most precious of gems, diamonds have been sought after by people of almost all cultures. Who has desired it for its beauty, defined by sleek cuts, light reflectivity, and brilliance all made possible by the artistry of the jeweller. 

However, when it comes to the diamond's colour, the idea appeared to be firmly set. Diamonds are colourless gemstones, that are valued in accordance to their carat-how big they are; cut-the type and quality of the gemstone’s dimensions and facets; clarity-the presence or absence of inclusion, and colour-which corresponded to the lack of secondary shades of yellow or brown.

Thus the idea of coloured is a new variable that enters the mix. In this Education page, we will explain what is meant by coloured diamonds and how they differ from the more popular colourless variety.

What is a Colourless Diamond?

When it comes to understanding the differences between coloured and colourless diamonds, it is important that we start by understanding what is meant by diamonds. Diamonds are carbon-based gemstones: meaning the sole element in the world-famous is carbon (C). What sets the diamond, however, that is from the other forms of carbon formation such as coal and graphite, is its unique atomic structure.

To get into the technicalities a bit, diamonds form when the carbon atoms are structured tetrahedrally: where each carbon atom is attached to the other four carbon atoms in the shape of a tetrahedron. This unique organisation of carbon atoms gives diamonds great durability, and in their hardened state, they emerge as valuable gemstones. As diamonds are hardened carbon, with a distinct atomic character, they naturally feature no colours. Or at least, colour or the presence of specific hues such as blue, green, and red, as seen in other top gemstone types is not common.

What is common however is the prevalence of a certain yellowish shade that features in a variety of technically colourless diamonds. This is due to the presence of various levels of nitrogen which is detected in carbon-based gemstones. And when it comes to diamond quality with respect to colour (one of the 4Cs of diamond quality) this idea of colour (that is the presence of various shades of yellow with increasing levels of concentration) is viewed as a negative factor.

So in the D – Z scale which measures diamond colour, gemstones which are closer to the D – H range (the high-quality ones) are those which feature a low to no presence of this yellow shading. Thus in colourless diamonds the lower the colour, the higher the quality. With coloured diamonds, things work a bit differently as we shall see next.

What are Coloured Diamonds?

Coloured diamonds or fancy coloured diamonds as they are sometimes known are a different class of diamonds, which are distinguished by the presence of distinct hues. These fancy-coloured carbon-based stones are known by some popular coloured variants such as blue diamonds, yellow diamonds, pink diamonds and the world-renowned Argyle diamonds.

When it comes to coloured diamonds there is a key difference in kind. Notable here are certain coloured diamonds that do not feature in the range of gemstone-quality coloured diamonds. At for in the recent past. Notable here are brown and black diamonds. Historically these coloured diamonds have been prominent in industrial use and are generally not considered a part of the fancy coloured diamonds range. Though that has started to change in recent times. 

It is important to note that coloured diamonds are real diamonds in that they share much of the same chemistry as colourless diamonds. Hence the strengths of colourless diamonds like scoring a full 10 on the Mohs scale for hardness also apply to them.

What Gives Coloured Diamonds Their Colour

For discussion, the main focus is on the top coloured diamond types: these are blue diamonds, pink diamonds, yellow diamonds and the famous pink and related red diamonds. When it comes to coloured diamonds, the first question that comes to mind is the origins of colour in this gemstone.

Diamonds, unlike other top gemstones, are generally more resistant to trace minerals, which often enter the formation of these minerals during the process of their formation deep beneath the Earth’s surface. Since diamonds, like another top gemstones, form over the course of tens to hundreds of millions of years, they are exposed to numerous other elements and chemicals. Other minerals that form into gemstones absorb these materials (known as trace minerals) much more easily, hence the prevalence of colour. Notable here are the corundum and beryl family of gemstones.

With diamonds, things are a bit different. Given their unique crystal structure, this phenomenon is quite rare, hence the presence of natural colour in diamonds is much rarer. Thus diamonds that do feature colour are more expensive. With the exception of nitrogen is generally more prevalent and hence contributes to the various shades of yellow tint in lower quality (colourless) diamonds. This is why in the world of coloured diamonds proper, the yellow variant is the most common.

However, things are a bit different when we consider two other top-coloured diamonds such as pink and green. These are points we will engage in dedicated posts, but for now, it suffices to say that the origins of colour in diamonds do not generally follow the trace mineral path, and often they are quite mysterious which adds to their value proposition.

Diamond Quality Factors: Coloured vs Colourless

When it comes to the difference between coloured diamonds and colourless diamonds a question you are likely to ponder is what factors should I look for when trying to pick a top-quality diamond of either variety? Well when it comes to colourless diamonds, the plain is rather well set. When it comes to picking a top-quality diamond: you look for the gemstone’s carat, cut, clarity, and colour (i.e. the absence). Here the standards are quite clear-cut. When looking for a top-quality diamond the type of cut: whether it's princess, round brilliant etc. is a key consideration. In terms of carat, the larger the number the better and more expensive the stone, and with clarity the fewer the number of inclusions and other inconsistencies on the surface and inside the stone.

With colourless diamonds, colour is the primary consideration. However, the other factors that make up the 4Cs count as well. With larger, clearer, well-cut-coloured diamonds being valued more. Critically when it comes to coloured diamonds, a key consideration is the type of colour in question and its concentration. Certain coloured diamonds are valued more than others, and also the level of colour. This will be explained in the following table.

Breakdown of the Differences between Coloured and Colourless Diamonds

Colourless or Coloured Diamonds: What Should you Go For?

Truly there is no simple answer to this question. When it comes to picking a top-quality gemstone, diamonds invariably feature at the top of the list. With the colourless diamond or ‘diamonds’ being a natural choice for their endurance, brilliance and long-term value. Coloured diamonds on the other hand are a premium choice. A choice for collectors or for those who really wish to stand out with their choice of a gemstone as in for an engagement ring. However, for some, the traditional colourless white diamond is the way to go.