Last updated on January 20, 2021
You might think that colourless diamonds are the most expensive and sought after stones available on the market, but some coloured diamonds are much more expensive and even harder to find. Such is the case with blue diamonds which are beyond the reach of most of our budgets. Let’s take a detailed look and find out how to choose a blue diamond.
How to Choose the Colour of Blue Diamonds
Natural blue diamonds owe their colour to the rare chemical element boron, which makes up only about 0.001% of the earth’s crust.
The diamond gets blue colour if the nitrogen content is low and there is boron present in its chemical structure. The higher the concentration of boron, the more intense the blue colour. The darker the blue, the more expensive the stone.
According to the GIA blue diamonds are classified using the following colour grades: Faint Blue, Very Light Blue, Light Blue, Fancy Light Blue, Fancy Blue, Fancy Intense Blue, Fancy Vivid Blue, Fancy Dark Blue, and Fancy Deep Blue. The secondary hue is also included in the grade if it is present, for example, Fancy Greenish-Blue.
The colour evaluation of blue diamonds has three main components: hue, saturation and tone.
Hue is the visible colour of a diamond and the primary hue of blue diamonds is blue.
There can also be secondary hues which greatly affect the value of stones. The most common secondary hues present in blue diamonds are green and grey.
Secondary hues that enhance the primary hue or do not detract from it add the value as a rule. Natural blue diamonds with no secondary hues are extremely rare and pricy.
This characteristic refers to the intensity of the colour.
As a general rule, the more saturated the colour of a diamond, the more valuable it is. That is why the diamonds that have pale or faint blue colour are less valuable than those with deep and vivid blue colour.
This characteristic refers to how light or dark the colour is.
The choice of the tone depends on your personal preference, however, the stones that are somewhere in the middle are the most sought-after.
The colour grade of blue diamonds is assigned based on saturation and tone.
How to Choose the Clarity of Blue Diamonds
The clarity of blue diamonds is graded the same way as that of colourless stones. The fewer inclusions, the higher its clarity grade.
Of course, high clarity blue diamonds are more valuable, but this characteristic is not crucial for fancy coloured diamonds. The blue colour tends to hide imperfections, so the appearance of blue diamonds is less affected by flaws compared to white diamonds.
When choosing the clarity of blue diamonds, look for a stone that is eye clean, meaning the diamond should not have inclusions visible to the naked eye.
Blue diamonds in the SI1-SI2 clarity range may look stunning and do not differ significantly from diamonds in VS or even VVS range.
How to Choose the Cut of Blue Diamonds
Unlike colourless diamonds, blue diamonds are not cut to maximize brilliance and sparkle. Blue diamonds are cut to achieve the best colour possible. In other words, the proportions that are considered ideal for colourless diamonds will not always be the best to bring out the colour of blue diamonds.
So when choosing a blue diamond, you should focus more on the stone’s colour intensity and hues, rather than judge the diamond using traditional cut grades.
Blue Diamonds and Carat Weight
Blue diamonds are extremely rare and they are among the most expensive coloured diamonds on the market. A good quality 1-carat blue diamond can cost up to $100,000.
Bigger blue diamonds are even harder to find, which is why they cost disproportionally more per carat.
As you increase in colour intensity, blue diamond prices extend beyond $200,000 per carat. Certain colour combinations such as blue diamonds with grey secondary hue are more affordable, they cost in $30,000 – $40,000 range.
Cover image credit: DIACORE