Clarity is the number one thing you need to look for when buying a diamond, especially in natural stones.  A poor clarity can mean visual blemishes in the stone, poor reflection or refraction of light, and even reduce the structural strength of a diamond.

Generally the higher the clarity of the stone, the higher the value, with the very highest grades often nicknamed ‘Investment Grade’ or ‘Museum Quality’. Despite the clarity of a diamond being important to both the value, appearance and structural integrity of the stone, it is important to remember that it diamond clarity does obey the law of diminishing returns.

For instance, a higher quality diamond might have a much higher value, but its actual visual improvement to a slightly lower clarity diamond may be indistinguishable to the untrained eye.

When diamond clarity is being judged it is often viewed under 10x magnification, so if you are under a budget, small flaws might not be a huge issue (depending on the kind of flaw and its intensity!). Generally if a diamond is classed as having a slightly included or included flaw, it has a flaw that is potentially visible to the naked eye.

Before buying a diamond you should also look for clarity enhancement. Clarity enhancement is not necessarily a bad thing, but it does mean that some flaws have been artificially filled.  Artificially filled diamonds are often referred to as fracture filled diamonds. If a diamond has undergone clarity enhancement, they must disclose this at time of sale. Clarity enhancement can greatly reduce the value of a diamond, since the filling is not as durable or long lasting as the diamond.

Most diamond flaws are categorized under either Inclusions or blemishes.

Inclusions refer to internal flaws in a diamond, and are often referred to as ‘internal characteristics’. Natural diamonds are particularly susceptible to inclusions as they are naturally imperfect. And nearly always develop at least some form of clouding and feathering as well as containing impurities of various other minerals and elements.

Other inclusions include knots, cavities, cleavage, bearding, internal grain, and even unnatural occurrences such as laser lines from their cutting process.

Blemishes are external flaws and often come from wear on the diamond or errors during the cutting and polishing process. Flaws such as scratches, nicks, chips and breaks are all blemishes, you can also find blemishes such as polish lines and natural external blemishes

Diamond Clarity is rated on the GIA diamond clarity grading scale (Gemological Institute of America). The GIA has six separate categories under which diamonds are graded..

• Flawless
• Internally Flawless (IF)
• Very Very Slightly Included (VVS)
• Very Slightly Included (VS)
• Slightly Included (SI)
• Included (I)

Flawless is the most valuable, and ranks highest in the GIA clarity grading scale.  It means that even under 10x magnification, no flaws could be found.  Whilst included category diamonds generally have flaws visible to the naked eye.

After a diamond drops below the Internally Flawed category there are also different grades. The grade represents the severity of a flaw, where a higher number represents a more serious flaw.

For example, an SI1 diamond is worth more than SI2, since an SI2 has a more visible flaw.

This grading scale is used nearly completely by the industry with only a few exceptions (which are based on a similar scale

How is the clarity of a diamond decided?

The clarity of a diamond is based on its internal flaws and their characteristics.  When a diamond has smaller and less obvious flaws, it generally ranks much higher on the GIA diamond clarity grading scale. Only the most noticeable flaws are used in the grading of a diamond, less obvious flaws are for the most part ignored.

Diamonds must be loose (not set in jewelry) to be accurately graded, and are judged on five key clarity factors.  These factors are Size, Number, Position, Nature and the color/relief of the flaw.

The Size and Number factors of clarity grading are fairly self-explanatory. Larger and more numerous flaws can significantly lower the grade of a diamond.

The position of a flaw is a little less obvious. A flaw under the table (The flat top of the diamond) is more easily visible, and one close to the service is often named a reflector (because it can be reflected multiple times by the diamond). (If a flaw is reflected, each reflection is counted as a separate flaw!).

The nature clarity factor is the definition of the flaw. This could be an internal or external characteristic such as a feathering, scratch or knot. Depending on the nature of a flaw the grade of the diamond can change significantly.

The color/relief is the final factor used in judging quality.  In the majority of cases the color itself is not as important as the contrast (relief) of the color to the rest of the diamond. A deeper relief and a higher contrast will give you a much more visible flaw which will have a much larger effect on the value of the diamond.

The value and rarity of a diamond are hugely influenced by its clarity rating, and you should definitely pay attention to a stones clarity before purchasing it. Look at the grade, and any notations regarding the flaws. It often makes sense to buy a stone that has average flaws, as its price will generally be more affordable, and the flaws may not be visible unless viewed under a microscope.