Clarity Characteristics of Diamonds – Feathers Clouds & Twinning Wisps

SI1 Feather shown within a large Emerald cut eye-clean diamond.

Photo shows the visibility of a small feather seen below the table facet of an Emerald cut diamond. 

Clarity Characteristics of Diamonds

Today’s post is devoted to the clarity characteristics of diamonds. There are many descriptions fitting for diamond inclusions. Today I’ve added each characteristic with a detailed description for each characteristic.

Study most GIA diamond grading certificates and you will often see words such as ‘feather’ or ‘twinning wisp’ for clarity characteristics within the diamond or extending into the stone from the surface (inclusions), unless graded Internally Flawless.

A-Z of Clarity Characteristics of Diamonds.

Please note that most of the following clarity characteristics will usually be very discreet, many only visible with a 10x lens and a trained eye. When appearing on a diamond certificate they merely identify and specify the type of inclusion.

Bearded Girdle (BG)

Often formed as a result of the manufacture and cutting of the polished diamond. Microscopic feathers extend from the surface of the girdle (outer edge) into the diamond.

Bruise (Br)

A small mark on the diamond, resulting from impact, which extends into the diamond, below the surface of the stone. These small marks often appear where two facets meet where the diamond is more exposed to damage.

Cavity (Cv)

Where part of a feather (see below) breaks away from the diamond, a small crack-like opening, the cavity appears.

Chip (Ch)

Impact, or pressure can cause diamonds to chip. Chips are damage and can vary in size and shape, but typically appear as breaks in the stones surface, often seen at the point of the diamond, edge of a facet or culet of the stone.

Cloud (Cld)

Clouds are formed by much smaller inclusions grouped in one area. Alone they are too small to be readily visible, but together they are more noticeable but of a more foggy and less distinct.

Feather  (Ftr)

A white inclusion, feather-like in appearance, (hence the name) usually formed by a fracture within the diamond.

Grain Center (GrCnt)

Caused by distortion of the diamond crystal, appearing either as light, or darker markings within the diamond usually thread-like or of pin-point appearance.

Crystal (Xtl)

Inclusions caused by crystallized mineral inclusions.

Indented Natural (IndN)

This can be the result of a natural indent within the rough-diamond appearing in the polished diamond’s surface. If a crystal within the diamond reaches and falls away from the surface upon cutting and polishing the diamond, this can also reveal a natural indent within the surface of the stone.

Internal Graining (IntGr)

Lines, Curves and inclusions appearing at angles. Can be white, coloured or semi-transparent, caused by irregularities during diamond crystal formation.

Knot (K)

This is a transparent included diamond crystal present within the diamond itself, extending to the surface following the process of cutting and polishing.

Laser Drill Hole (LDH)

A fine, straight hair like line which extends from the surface of the diamond. Laser drill holes are the result of a beam of laser drilling into the diamond, typically part of the process for clarity treatment. (Which should be disclosed by those selling such clarity enhanced diamonds.) These are usually best seen at an angle and extend from a microscopic pin-prick size hole anywhere on the surface of the diamond.

Needle (Ndl)

This type of inclusion appears as thin, needle-like inclusion, which can vary in length.

Pinpoint (Pp)

A small dot-like inclusion, within the diamond.

Twinning Wisp (W)

“A series of pinpoints, clouds or crystals that forms in a diamond’s growth plane ; associated with crystal distortion and twinning planes.” (GIA definition.)

How do Diamonds form and why are some more included than others?

Unique Diamond inclusions appear in most Diamonds. These inclusions are a result of the intense heat and pressure of the Earth’s crust. These conditions alter the structure of the carbon atoms within the Diamond while it is being formed. The alteration that occurs is what causes Diamond inclusions to appear. Depending on the conditions, some Diamonds may have more inclusions than others. For example, a Diamond that has been under more extreme conditions may have many more inclusions than one that has not been under such extremes.

Diamonds form in various environments, which accounts for the differences in colour clarity and size.

Are there some Diamond inclusions that are worse than others?

In terms of what to avoid with Diamond inclusions, there are several factors to think about. You can also read more into the clarity grades of Diamond inclusions, and what this means for your Diamond.

Size of Diamond Inclusions

Diamond inclusions which are smaller in size can make a Diamond look eye-clean.  A Diamond with one or two larger inclusions will be more visible to the naked eye. Diamond inclusions that tend to be harder to see within a Diamond can include pinpoints, which look just like the point of a pin, and clouds, which are the same colour as the rest of the Diamond, so are therefore harder to see.

Type of Diamond Inclusions

Black spots, cavities and chips are all inclusions which are more likely to be visible. This is because they can be larger and darker. Black spots can look like frogspawn in some people’s opinion, just to give you an example. Chips within a Diamond, however, will alter the outer appearance of the Diamond more than anything. They may also weaken the structure of your Diamond if they are in the wrong place. You can visit our previous blog post on Diamond Clarity Characteristics for more information on the various Diamond inclusion types.

Position of Inclusions within a diamond

Diamond inclusions on the table of the Diamond are going to be more visible, and therefore less desirable. You may not find this a problem, however. Most jewellers tend not to sell Diamonds with table inclusions for this exact reason. Diamond inclusions further into the Diamond can have both pros and cons too though. They can be well hidden within the facets. But, if they are in just the wrong place, they can be reflected in the other facets. This can make it look like one inclusion is multiplied many times. Some Diamond inclusions are strategically hidden by claws, too.

Diamond cuts and Inclusions

Diamond inclusions are less visible in some cuts of Diamond. Emerald cuts, for instance, are ‘honest’ stone cuts. Inclusions are not easily as hidden in an Emerald cut as it has fewer facets. On the other hand, Round Brilliant cut Diamonds are more likely to be able to ‘hide’ inclusions. This is because they have more facets.

Diamond Laboratory Grading

Diamond inclusions are often referred to as Diamond characteristics. This is because Diamond colour and clarity can vary depending on the person grading them. A universal standard is adhered to, but this can differ ever so slightly from laboratory to laboratory. For Example, GIA (The Gemological Institution of America) tend to be very exacting with their grading.

GIA and IGI clarity grades compared

The above picture shows two Diamonds which have been graded the exact same colour and clarity. The one on the left has been graded by IGI. The one on the right, by GIA. GIA tend to be more strict on their grading. Therefore the one on the right has fewer small inclusions, while the left-hand Diamond has more small Diamond inclusions dotted throughout.

For more information don’t forget to stop by our diamond education section of the website.

Mark Johnson

About Mark Johnson

Mark attended Liverpool University and went on to pursue a career in the diamond industry. After more than a decade working in polished diamonds, Mark moved to the Isle of Wight where he launched Serendipity Diamonds. He works most days from their busy Ryde showroom, photographing jewellery and writing for the Serendipity Diamonds website. Anyone interested can connect with Mark on Linkedin via the profile link.

Mark Johnson

About Mark Johnson

Mark attended Liverpool University and went on to pursue a career in the diamond industry. After more than a decade working in polished diamonds, Mark moved to the Isle of Wight where he launched Serendipity Diamonds. He works most days from their busy Ryde showroom, photographing jewellery and writing for the Serendipity Diamonds website. Anyone interested can connect with Mark on Linkedin via the profile link.