Clarity is one of the all-important 4Cs of diamond grading. A diamond’s clarity is highly important, as natural features within the stone can obstruct a diamonds brilliance, fire, and scintillation.

To ensure you purchase a quality diamond with a good clarity, it is important to understand the clarity criteria and know what grades are best suited for your budget, balanced with carat weight and colour and cut grades. Our diamond clarity explanation, together with diamond clarity chart will help you to understand the GIA ratings for a flawless to imperfect diamond, and every grade in between!

A diamond’s clarity is its freedom from inclusions and blemishes. Inclusions are the internal characteristics within the stone that appear when the diamond crystal is formed, and so are inevitable for the majority of diamonds. Very few natural diamonds are flawless, and many contain inclusions such as enclosed minerals, growth lines, and fractures. Inclusions were formerly called flaws or carbon spots, and can be seen either with the unaided eye or with the help of a 10x magnification lens (known to the trade as a loupe).

Blemishes are external characteristics of a faceted diamond. These can include features such as polishing marks, burn marks and the presence of naturals on the diamond’s girdle. These features are subject to a diamond’s quality of polish, and so are only really taken into consideration when deciding between a flawless and internally flawless diamond clarity grading.

Both internal and external features could affect the brilliance of the stone. The return of light from the inside of the stone and the reflection of light from the surface of the stone both contribute to a diamond’s unique beauty in its brilliance, fire and scintillation. Lower clarity grades on the scale can even affect the durability and longevity of the diamond. 

Diamond experts grade the clarity of a diamond by examining the stone face-up under 10x magnification, illuminated by a daylight lamp for internal features and external blemishes. The use of 10x magnification gives a reasonable field of view to assess inclusions deep within the stone as well as features that are on the surface of the stone. 

Diamonds are assessed for clarity loose, jewellery settings such as claws and bezels can affect the perceived clarity of the stone by obstructing the view of inclusions and blemishes.

The GIA grading criteria for clarity is as follows:  




No inclusions or blemishes seen under 10x magnification.

Internally Flawless

No inclusions and insignificant blemishes seen under 10x magnification.


Inclusions are extremely difficult to see under 10x magnification


Inclusions are very difficult to see under 10x magnification.


Inclusions are difficult to see under 10x magnification.


Inclusions are somewhat difficult to see under 10x magnification.


Inclusions are easy to see under 10x magnification.


Inclusions are very easy to see under 10x magnification, may be seen with the unaided eye.


Obvious inclusions, the beauty and durability of the stone are somewhat affected.


Obvious inclusions, the beauty and durability of the stone are seriously affected.


Obvious inclusions, the beauty and durability of the stone are very seriously affected.


When assessing a diamond’s clarity grading, the following key considerations are important.

  • The quantity of inclusions within the stone. The more inclusions there are within the stone, the more of a visual impact they will have under 10x magnification. A diamond with more inclusions is generally graded lower than a diamond with few inclusions, all other factors being equal.
  • The type of inclusions seen. Different types of inclusions can be seen within diamonds, from bulky crystal inclusions, to tiny fractures known as feathers, to pinpoint inclusions. Darker inclusions are graded more harshly than lighter coloured inclusions that are less obvious under 10x magnification.
  • The size of the inclusions. Clarity is graded under 10x magnification. If an inclusion is so microscopic it cannot be seen under this level of zoom, then it will not be taken into account in the clarity grade awarded. On the other hand, if an inclusion is so large it can be seen with the unaided eye, the clarity grading cannot be higher than an SI2.
  • The placing of the inclusions. Inclusions that are directly underneath a table facet will have a big visual impact on the overall appearance of the stone, and so will produce a much lower clarity grade than those with inclusions underneath the crown facets. The worst place for an inclusion in a round brilliant cut diamond is lower down in the pavilion as the optical effects of the diamond can cause a kaleidoscopic effect reflecting a single inclusion several times over.

Laboratory reports often feature diagrams that plot the location and nature of the inclusions and blemishes of the stone, to help demonstrate the reasons behind the clarity grade. It takes years of experience to pinpoint some diamond inclusions, so opting for a diamond with a GIA, IGI or HRD certificate provides buyer protection and a peace of mind as to the quality of the diamond.

Speak with our team of diamond jewellery specialists for more advice on diamond assessment, grades and cuts. Buy diamond engagement rings and jewellery online, call us on 01335 453 453 or email us at