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During a diamond's formation, they can inherit blemishes and/or inclusions. To determine the quality of the diamond, they are put under 10x magnification.
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Diamond Four Cs Guide: Clarity

Lewis Findley
Lewis Findley

Four Cs of a Diamond - Clarity

In this guide you'll learn about clarity and how inclusions and blemishes can impact a diamond's value.

You can liken them to birthmarks that are inherited during their formation deep in the Earth, at over 1,204 degrees celsius, or during the cutting process.

Highly-prized diamonds contain as few inclusions and blemishes as possible but they command huge prices. 

Diamond clarity is one of the least important factors when choosing to buy a diamond because most diamonds have blemishes and small inclusions that are microscopic and they are unable to be seen with an untrained or unaided eye.

But, what are diamond inclusions and blemishes? How are they graded?

What are diamond inclusions?

Video by - Cape Diamonds.

Diamond inclusions are internal to a diamond and form during their creation under huge amounts of pressure and heat.

The closer the inclusion is located to the centre of the table, the more it can affect the clarity grade. In addition, they can even be reflected by the different facets of a diamond if they are located in places like the pavilion.

Diamond cutters will strive to exclude as many inclusions as possible. If any are present, they will be placed in areas hard to see. 

Examples include the girdle, around the bezel or where the diamond is set in a ring.

What are diamond blemishes?

Diamond blemishes are external to a diamond and appear during their formation and/or during the cutting process. 

Unlike inclusions, blemishes can be polished away as they are on the surface of the diamond. 

Between inclusions and blemishes, inclusions will have a greater impact on the way light interacts with a diamond. The reason why is because they have penetrated the diamond and their unique nature will affect the diamond's overall clarity. 

how to measure diamond clarity

Diamond Clarity Scale

Image Via - your diamond teacher

To ascertain the clarity of a diamond, they are scrutinised under 10x magnification where the assessor will look for the presence of inclusions or blemishes.

During this scrutiny, the assessor will identify every flaw of the diamond by determining the total amount, position, colour, nature and size.

Once this process has been done, the clarity of the diamond will be identified against six categories and an 11-point diamond clarity scale created by the GIA.

Diamond Clarity Scale

Starting at flawless, the scale ends with inclusions included. Some categories have sub-categories too which exist to get a greater understanding of the clarity.

FL (Flawless) 

A flawless diamond is as the name suggests, sublime.

These ultra-rare diamonds will contain no inclusions or blemishes. Did you know that only 1 in 5,000 diamonds are rated as flawless?

IF (Internally Flawless) 

As you already know, diamonds that are internally flawless contain no inclusions but blemishes can be present. 

These stones appear identical to a flawless diamond but they can contain signs of polishing. However, 10x magnification helps to make the distinction. 

The CTF Pink which became the most expensive diamond ever bought at auction was rated as Internally Flawless. 

VVS1 and VVS2 (Very, Very Slightly Included)

The first category with sub-categories. However, telling the difference between the two can be a challenge, even for a skilled observer.

The tell-tale sign is the location of the graining or marks. To give you an idea, here is a rule of thumb.

  • VVS1 - Inclusions that are visible from the pavilion (bottom part of the diamond). 
  • VVS2 - Inclusions that are only visible from the crown (top part of the diamond).

Diamonds of these grades are highly prized due to being near-perfect and priced accordingly. 

VS1 and VS2 (Very Slightly Included)

As you read earlier, a diamond cutter can leave inclusions in different parts of a diamond and an assessor can struggle to find them.

However, with magnification (a jeweller's loupe), they can be identified. The difference between these two categories are the size and frequency of the inclusions.

  • VS1 - Inclusions that are smaller or less frequent than those in a VS2-graded diamond.
  • VS2 - inclusions can be big enough to see under magnification but not the naked eye.

Despite these minor differences, their prices can vary by a large margin.

S1 and S2 (Slightly Included)

In these ranges, assessors will be able to view inclusions with greater ease under magnification.

What becomes apparent are white, black or grey marks around the crown and pavilion.

  • SI1 - Contains noticeable inclusions which are easy to see for a trained assessor.
  • SI2 - Contains inclusions that are plain to see for the assessor.

Diamonds under this classification can also be seen by the naked eye. However, they can appear to look like VS diamonds, so scrutiny is needed.

I1, I2, and I3 (Inclusions Included)

The bottom part of the scale with a triple sub-category. These diamonds are laden in inclusions to the point where they are seen by the naked eye quite easily. 

In addition, these diamonds tend to have problems with durability.

  • I1 - Contain inclusions that have colour (usually dark) and of noticeable size. 
  • I2 - Contain inclusions that are more frequent than an I1-graded diamond but it's here where questions of durability begin.
  • I3 - Have potential problems with durability.

It's possible to boost the clarity of a diamond, albeit artificially. This process is called enhancing and involves exposing the diamond to a laser. 

How are diamonds treated?

Diamonds are treated to improve their natural clarity. 

Examples of the methods include drilling into an inclusion, with a laser, and pouring acid into the hole from the top of the diamond.

Tip - to identify a hole formed by a laser, they appear as a white dot from the top or a white line from the side.

In addition to erasing inclusions, a diamond can be enhanced to fill cracks and fractures. This involves filling the diamond with a glass-like clear material.

Note - diamond assessors like the GIA will not grade diamonds where cracks and fractures have been filled.

Finally, to improve the colour of a diamond, they can be exposed to mass amounts of heat to remove any discolourations.

Final Words

The process used to determine the clarity of a diamond is as immense as their formation!

When profiling the diamond you're looking for, use clarity along with the other Cs to identify that perfect diamond.

It's important to remember that with clarity, the grade can affect the price, so factor that into your budget.

In regard to buying an I-graded diamond, be aware that they can have durability risks. 

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