Charles Rose

Sparkling. Scintillating. Spectacular. Whether elegantly understated or strikingly dramatic, diamond jewellery always dazzles, so it’s no wonder that this gemstone is an enduringly popular and treasured staple of every fine jewellery lover’s personal collection. But how much do you know about the features of a diamond? When you purchase any diamond jewellery piece, you will feel more confident about your gemstone selection if you understand the structure of a diamond. We at Charles Rose want to make the experience of buying diamond jewellery as easy and informative as possible with our helpful guides to the 4Cs of diamond quality: cut, colour, clarity and carat weight.

This comprehensive guide will explain the fundamentals of the third most important diamond characteristic: clarity.

What is Diamond Clarity?

diamond clarity and inclusion chart

Diamond clarity is a general term used to describe things in a gemstone that obstruct the passage of light reflected through the diamond. Have you ever noticed how some diamonds shimmer and flash stunning kaleidoscopic colours while others appear dull and lacklustre? This has to do with a diamond’s clarity.

Light reflects and scatters off a diamond’s surface, creating the mesmerising sparkle synonymous with this much-loved stone. However, if the light’s path is blocked in any way, it will hinder the diamond’s light performance, minimising its brilliance and sparkle. 

Natural diamonds form deep within the Earth’s crust under extreme pressure and temperatures. Consequently, diamonds often form with internal (inclusions) or external (blemishes) markings, making every diamond unique in appearance. Virtually all diamonds and other precious gems contain inclusions. However, some imperfections are so minuscule, they do not affect a stone’s grading.

Inclusions in a diamond encompass small marks in the stone, like tiny fissures, minerals or foreign crystals that may or may not affect a diamond’s clarity. Generally, the fewer inclusions, the more valuable the diamond. Blemishes include scratches, knots, chips and cavities that the diamond cutting and polishing process have not removed from the original rough diamond.

Few natural diamonds form without any internal and external markings. Such rare gemstones are graded as flawless on a diamond clarity chart which typically ranks stones using magnification tools. Flawless diamonds are considered some of the most valuable gems in the world. When discussing diamond clarity, diamantaires refer to the absence of inclusions or blemishes in all but the very rarest of diamonds.

Diamond Clarity Chart

The diamond clarity chart is based on the universally recognised Gemological Institute of America (GIA) grading scale. Expert gemologists use a 10x magnification lens to evaluate the presence or absence of internal inclusions or surface blemishes in the stone. After assessing and classifying clarity characteristics, each diamond is assigned a clarity grade based on the following scale, ranked highest to lowest:

  • FL (Flawless): Flawless diamonds show no internal or external imperfections under 10x magnification. These gemstones are very rare and account for less than 2% of the world's diamonds.

  • IF (Internally Flawless): Internally flawless diamonds show no inclusions but may have microscopic surface blemishes that are only visible under 10x magnification. These extremely small markings do not affect the diamond’s gorgeous sparkle or light reflection.

  • VVS1 & VVS2 (Very Very Slightly Included): These diamonds show very small inclusions that even trained gemologists find difficult to see using 10x magnification. Diamonds with very very slight inclusions are ‘eye clean’, meaning that there is no hint of a flaw visible to the naked eye.

  • SI1 & SI2 (Slightly Included). Diamonds classified as slightly included on the diamond grading chart mean that expert gemologists can find internal markings under 10x magnification. SI1 and SI2 graded diamonds are usually eye clean (inclusions are not visible to the naked eye).

  • I (1/2/3) (Included): Included diamonds have obvious flaws that are visible not only with magnification but can also easily be seen with the naked eye. The inclusions in I-graded diamonds can affect both durability and the stone’s brilliance and sparkle as these flaws obstruct how light is reflected.

Gemologists also assess and grade milkiness, as it can also significantly impact a diamond’s appearance and value. Milkiness refers to numerous tiny inclusions forming milky white or grey ‘clouds’ across a gem. Common milkiness grades are Nil (N), VSL (very slight), SL (slight), CVSL (centre very slight), CSL (centre slight), MED (medium) and Heavy.

What Characteristics Determine Diamond Clarity Grade?

Diamond specialists identify and classify several characteristics to determine diamond clarity grade:

  • Size: The size of inclusions is first assessed to determine clarity grade. Large inclusions visible to the naked eye often result in a diamond being classified as a lower clarity grade.   

  • Number: This refers to the number of inclusions and blemishes that are noticeable both under magnification and to the naked eye. The fewer visible markings in a diamond, the higher its clarity grade.

  • Position: An inclusion’s position on the diamond’s structure greatly determines whether this characteristic acts as a reflector. The closer the inclusion to the diamond’s table, the greater chance the inclusion is visible, while markings closer to the girdle are more difficult to see. Facets on the diamond’s pavilion function as mirrors and will reflect any inclusions located on this part of the diamond’s structure.

  • Nature: This refers to the type of marking present in the diamond – internal (inclusion) or external (blemish).

  • Colour and relief:  Colour and relief refer to how easily you can spot the difference between a marking and the diamond itself. When an inclusion is closer to the gem colour, it lowers its relief.

How Important Is Diamond Clarity?

The 4Cs of diamond quality all play a part in a diamond’s sparkle, beauty and value. When it comes to diamond clarity, Charles Rose recommend choosing a diamond that is ‘eye clean’ (meaning that markings are not visible to the naked eye) because inclusions and blemishes should never distract from a diamond’s brilliance, fire and scintillation. 

Just like the ideal cut, colour and carat weight, the best diamond clarity depends on your preference. After all, choosing the perfect diamond is a personal journey. Read our helpful guides on diamond cut, diamond colour, and diamond carat weight before making your final decision.

If you’d like to discuss the diamond 4Cs further and see our stunning collection of diamond and gemstone jewellery, book a consultation with our Charles Rose diamantaires at one of our Melbourne or Geelong showrooms.

Charles Rose – Australia’s premier fine diamond house and bespoke jeweller.