Diamond Clarity Factors

Diamond clarity factors 

Five factors determine the overall effect of characteristics on a clarity grade. Most of them have to do with how readily the grader can see the characteristics. The five factors are: 

  • Size 
  • Number 
  • Location (Position) 
  • Relief 
  • Nature 

The effect of size is obvious: Large inclusions affect clarity more than small ones. 

The number of inclusions is also important, but it’s not just a matter of counting them. A stone can have many tiny inclusions and still be high on the clarity scale. One or two of the largest inclusions usually set the grade. Also, an inclusion might be small and in an inconspicuous place. But if it’s reflected in the pavilion facets, it looks like many inclusions, not just one. When this happens, it’s called a reflector. Reflectors lower the clarity grade more than similar, non-reflecting inclusions. 

An inclusion’s location also affects its visibility. Cutters call the area right under the table the “heart” of the stone. Inclusions are much more visible there than they are under the bezel facets or near the girdle. 

Relief means the contrast between the inclusion and the diamond. Inclusions that are very bright, dark, or colored are easier to see, so they have a greater impact on the clarity grade than transparent inclusions. 

Nature refers to the type of characteristic and its potential effect on the diamond. For example, an optical irregularity in the crystal structure would have far less impact on clarity than a physical break in the diamond. Very deep feathers that extend from the crown to the pavilion pose durability concerns and can lower the grade. 


Inclusions and blemishes

Together, inclusions and blemishes are called clarity characteristics. Clarity characteristics help determine a diamond’s value, they can also help establish a gem’s identity and quality. Inclusions are inside the diamond or extend into the diamond from its surface, and blemishes are limited to the surface. Even very small clarity characteristics can have a large influence on diamond value. Blemishes usually only affect the top two clarity grades (Flawless, Internally Flawless), while inclusions affect all grades. 

Here are some common inclusion and blemish examples and brief definitions:

Inclusions:

Crystal (Xtl): A mineral crystal contained in a diamond
Feather (Ftr): General trade term for a break in a gemstone, often white and feathery in appearance
Cloud (Cld): Many tightly grouped pinpoints that might be too small to distinguish individually but together have a hazy appearance
Chip (Ch): A shallow opening that occurs at a girdle edge, facet junction, or culet; caused by damage to the stone’s surface
Bruise (Br): A tiny area of impact accompanied by very small, root-like feathers; typically occurs at a facet junction
Needle (Ndl): A thin, elongated crystal that looks like a tiny rod at 10X
Pinpoint (Pp): A very small crystal that looks like a tiny dot at 10X
Twinning Wisp (TW): A series of pinpoints, clouds, and/or crystals that forms in a diamond’s growth plane; associated with crystal distortion and twinning planes
Etch Channel (EC): (less common) An angular opening that starts at the surface and extends into the diamond

Blemishes:

Abrasion (Abr): A series of minute scratches and pits along a fashioned diamond’s facet junctions, producing a white or fuzzy appearance
Extra Facet (EF): A facet that’s not required by the cutting style, placed without regard for the diamond’s symmetry; most often found near the girdle
Natural (N): A portion of the original surface of a rough diamond left on a fashioned stone; usually on or near the girdle
Nick (Nck): A small notch on a facet junction with no readily apparent depth at 10X, usually along the girdle edge or at the culet
Pit (Pit): A small opening that looks like a tiny white dot at 10X
Scratch (Scr): A thin, dull white line across the diamond’s surface; shows no apparent depth at 10X
Rough Girdle (RG): Irregular or granular girdle surface

 

Source: Gemological Institute of America 

 

Aya Gem

Back to blog