While it looks like a droplet of pure light, a natural diamond is actually a solid form of carbon that has much in common with graphite, which is used as the lead in pencils. It’s fascinating that two polar-opposite substances are made from the same molecules; they’re just arranged very differently. Graphite has a layer formation, while diamond has three-dimensional bonds.
Diamonds are formed during an intense crystallising process involving heat, pressure and millions of years. It’s an uncontrolled process that happens deep within the planet, so no natural diamond is born without flaws, which are called ‘inclusions’ and ‘blemishes’. Inclusions are found within the diamond; blemishes are on the outside surface.
While you might hear people talk about ‘flawless’ diamonds, the word flawless really means ‘no visible inclusions or blemishes’. The flaws are there, but they can’t be seen without specialised instruments and an expert eye. If a diamond has inclusions too small to see at 10x magnification, they have no effect on the clarity grade.
What is the clarity of a diamond?
The word ‘clarity’ refers to a diamond’s inclusions and surface blemishes. To establish a clarity grade, a diamond specialist will look at the number, size, relief and position of inclusions and blemishes within and on a stone. This inspection can only be done before a stone is put in a setting, because the setting may hide some inclusions.
Inclusions in diamonds can be shaped like crystals, needles or wisps. Blemishes encompass things like scratches and nicks that exist only on the diamond’s surface.
Some inclusions may have no impact on value; they might even make the stone more interesting. Others may negatively affect the look of the diamond, as well as its structural integrity.
Which diamond clarity is best?
The GIA Diamond Clarity Scale has six categories, some of which have sub-categories. All up, there are 11 diamond grades on a diamond clarity chart.
Flawless (FL) – no inclusions and no blemishes can be seen by an experienced grader using 10x magnification.
Internally Flawless (IF) - no inclusions can be seen using 10x magnification, but the stone has some blemishes on the external surface, which can often be polished away.
Very, Very Slightly Included (VVS1 and VVS2) - inclusions are difficult for a skilled grader to see under 10x magnification. Most people shopping for a diamond can’t tell the difference between FL, IF and VVS diamonds.
Very Slightly Included (VS1 and VS2) - inclusions can be seen under 10x magnification, but are described as ‘minor’.
Slightly Included (SI1 and SI2) - inclusions are noticeable under 10x magnification, but not to the naked eye.
Included (I1, I2, and I3) - inclusions are obvious under 10x magnification and can be seen by the naked eye and can affect the brilliance of the stone. What’s more, the inclusions might impact the diamond’s long-term durability.
What colour and clarity is good for a diamond?
Colour and clarity are two different diamond characteristics. One refers to the hue of the diamond; the other refers to its transparency. Both colour and clarity affect the look of a diamond, so they should be considered together.
In general, the best white diamonds have no colour, while lower-grade stones have a slight yellow tint. Fancy coloured diamonds – which are highly valuable – are different, because they are can be bright yellow, red, pink, blue, purple, black and green. Clarity, as explained in detail above, refers to the presence of inclusions and blemishes that affect a diamond’s transparency.
When you’re buying a diamond ring, for romantic or investment reasons, it’s best to consider information about every aspect of the stone – cut, colour, clarity and carat (the 4Cs) - before you make your decision.
What's more important - cut or clarity?
There is an interesting interplay between cut and clarity. For example, if you’re considering a round brilliant, princess or pear-cut diamond, inclusions aren’t as noticeable. An emerald or asscher cut is different because the stepped nature of the cut makes inclusions and blemishes more obvious.