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4Cs of Lab Grown Diamonds: Diamond Colour

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At first glance, choosing the perfect colour might not immediately come to mind when selecting your next diamond. However, like the other “C”s in jewellery, colour plays an important role in a given stone’s aesthetic appeal and value.

In the world of jewellery, when it comes to colour, less is more. That is to say, a diamond with less colour is typically more rare and thus valuable than a diamond with colour. Most diamonds that fit this trend range from colourless, to being tinged with light yellow or brown. Note though, that there are a class of coloured diamonds that fall out of this norm, and are extremely rare and expensive. These stones, known as “fancy diamonds”, come in a wide range of exotic colours such as green, blue or even pink.

When examining a diamond’s colour, the standards and definitions for measurement don’t change based on whether it is a lab-grown or mined diamond.

Even though lab-grown diamonds are created by man, they are still susceptible to the same imperfections in mined diamonds, and hence can come in coloured variations.

A Guide to Understanding Diamond Colour: The GIA Colour Scale

The Gemological Institute of America uses a scale from D to Z to gauge the different colour grades of diamonds. This scale is used on both mined diamonds and their lab-grown counterparts.

At the top of the scale are D diamonds, which are colourless and extremely rare and expensive . At the bottom of the scale are Z diamonds, which are much more common and have either noticeable yellow or brown hues in them. As the scale goes from D to Z, diamonds go from being colourless to having more yellow or brown tones.

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Fig 1. This illustration showcases the relative colour profiles of diamonds with different colour grades.

Colourless Diamonds (D, E, F): These diamonds are colourless - to tell each grade apart, a special tool called a colorimeter is needed. Diamonds with a D grade are considered top tier with an absolutely colourless profile. Less than 1% of the world’s diamonds are considered D grade.

Near Colourless Diamonds (G-J):
Near Colourless Diamonds have small subtle tones of yellow that are extremely hard to discern unless they are compared against other diamonds. These diamonds are less expensive than completely colourless diamonds and make a good value based purchase.

Faint Yellow Diamonds (K, L, M): These diamonds have a slight yellow tint that you can see without any special tools.

Very Light Yellow Diamonds (N-R): In this range, from N to R, the yellow or brown colour in the diamonds is more noticeable.

Light Yellow Diamonds (S-Z): Diamonds in this group have clear light brown or yellow tones.

Beyond the range of the GIA scale comes fancy coloured diamonds. These diamonds come in a variety of vibrant colours, including red, purple, blue, and green. They're not common; in fact, only about 1 in 10,000 diamonds are considered 'fancy' by GIA standards. Given their beauty and extreme rarity, these stones can be quite expensive.

How Does Nature Determine Diamond Colour?

The hue of a diamond is largely determined by the presence of trace elements and structural anomalies in its crystalline structure, which are determined by the conditions present during the creation deep inside the earth's mantle.

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Diamonds can acquire a yellow shade due to having nitrogen impurities in its chemical composition, while boron imparts a sought-after blue colour. Nickel can cause diamonds to appear grey or yellow, and hydrogen is known to produce violet and grey shades in some diamonds.

Furthermore, deviations in the diamond's lattice structure during its formation can change how it absorbs and reflects light, leading to different colours that aren’t typically created from trace elements. For instance, if a diamond is subject to even more extreme temperatures and pressure than traditionally seen, it can take up a crystalline structure that gives off a pink hue.

In the lab-grown diamond world, advanced technology enables the creation of various colours and GIA colour grades by replicating the conditions that naturally produce these hues.

During the formation process in the lab, trace elements like those previously described can be added to help influence the diamond’s colour.

Furthermore, variations in the diamond's formation driven by either the High-Pressure High-Temperature (HPHT) or Chemical Vapour Deposition (CVD) can result in stones with different colour profiles.

With today’s technology, man has a means to create diamonds of all different profiles and colours, offering a highly precise and controlled means of producing a variety of diamonds that fit any occasion.

How Do Professionals Measure for Colour?

Assessing the colour of a mined or a lab-grown diamond is a sophisticated process best handled by experts.

This is because various elements, such as the diamond's cut and its setting, can influence how its colour is perceived. For example, diamonds placed in gold settings tend to look warmer, possibly altering their actual colour. Moreover, specific shapes like heart or marquise cuts can amplify a diamond's brilliance, potentially disguising its true colour.

Experts employ a variety of tools for precise colour evaluation of diamonds. These tools include colour grading loupes for a detailed examination, UV lights to reveal fluorescence that might affect colour appearance, microscopes for thorough analysis, spectrometers to study the light the diamond absorbs and emits, and master stones, which are benchmark diamonds with established colour grades for comparison. These instruments and methods guarantee an accurate and consistent colour grading, conforming to recognized colour measurement standards.

Finding the Perfect Diamond

In conclusion, the colour of a diamond is a critical aspect that significantly impacts its value and visual appeal.

Like with all C’s of diamonds though, it’s best to weigh them against each other to ensure you get a stone that fits your style and budget. In the end, the perfect diamond isn’t just about having a stone that’s completely colourless, or one that has a fancy hue, it’s about finding one that balances with your taste and budget. Whether you prefer a classic, colourless gem or a unique, faintly tinted stone, modern day technology now enables you to find the perfect stone you’re looking for.

At Vena Nova, we have years of experience in the diamond industry, and also have a graduate gemologist on staff so you can be sure to be properly informed when buying your next stone. We warmly invite you to our showroom in downtown Calgary, where we feature one of the largest collections of loose lab-grown diamonds and jewellery in Canada.