A diamond is assigned a clarity grade based on the number and placement of internal features (inclusions) and surface characteristics (blemishes) that are visible under 10x magnification. The GIA Clarity Scale contains eleven clarity grades ranging from Flawless to I3.
The GIA Diamond Clarity Scale has 6 categories, some of which are divided, for a total of 11 specific grades.
- Flawless (FL)
No inclusions and no blemishes visible under 10x magnification
- Internally Flawless (IF)
No inclusions visible under 10x magnification
- Very, Very Slightly Included (VVS1 and VVS2)
Inclusions so slight they are difficult for a skilled grader to see under 10x magnification
- Very Slightly Included (VS1 and VS2)
Inclusions are observed with effort under 10x magnification, but can be characterized as minor
- Slightly Included (SI1 and SI2)
Inclusions are noticeable under 10x magnification
- Included (I1, I2, and I3)
Inclusions are obvious under 10x magnification which may affect transparency and brilliance
Many inclusions and blemishes are too tiny to be seen by anyone other than a trained diamond grader. To the naked eye, a VS1 and an SI2 diamond may look exactly the same, but these diamonds are quite different in terms of overall quality. This is why expert and accurate assessment of diamond clarity is extremely important. When diamonds are graded, they are magnified at 10x power. Evaluating a diamond’s clarity involves determining the number, size, relief, nature, and position of these features, as well as how these affect the overall appearance of the stone. While no diamond is perfectly pure, the closer it comes, the higher its value.
How did the GIA Clarity Scale come to be?
GIA’s clarity grading system was developed because jewelers were using terms that could be misinterpreted, terms like “loupe clean” or “piqué”, which are still used by the International Diamond Council (IDC).
Piqué Clarity, or P Clarity is the European term for “Imperfect“. It is actually a French name meaning “Mark“, “Blemish“, or “Pricked“. Piqué is equivalent to GIA’s “I Clarity Range” (I1, I2 and I3), which stands for “Included” or “Imperfect”.
A Diamond’s Clarity Refers to the Absence of Inclusions and Blemishes
Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep in the earth. This process can result in a variety of internal features called “inclusions” and external characteristics called “blemishes.” Small crystals can become trapped in a diamond when it’s forming. Sometimes as a crystal grows it can develop irregularities in its atomic structure. For natural diamonds, these “inclusions” and “blemishes” give the diamond its unique character and identifying fingerprint.
Types of Inclusions: (internal features)
- Crystal– a tiny piece of another mineral trapped inside of the diamond during growth (often black in color).
- Pinpoint– a very small crystal that looks like a tiny dot at 10x magnification.
- Cloud– many tightly grouped pinpoints that might be too small to distinguish individually but together have a hazy appearance.
- Feather– general trade term for a break in a gemstone, often white and feathery looking in appearance.
- Knot- a tiny crystal which goes against the diamond’s grain and protrudes through the stone’s surface.
- Bruise- a tiny area of impact accompanied by very small, root-link feathers; typically occurs at a facet junction.
- Needle– thin sharp looking inclusion, usually white or transparent.
- Bearding- tiny hair-like inclusions which form at the surface of the girdle and go into the stone.
- Internal Graining- internal irregular crystal growth that resembles lines. This may cause the stone to appear foggy.
- Cleavage- tendency of the stone to break in a certain direction resulting in smooth surfaces.
- Twinning Wisp– lines visible inside a diamond that look like ripples.
This inclusion is a result of growth defects in a diamond’s crystal structure. During a diamond’s formation process, it may stop growing due to unfavorable conditions and twinning wisps will form when growth restarts (thousands of years later) in a different direction. Essentially, twinning wisps are a mish-mash of different inclusions such as pinpoints, crystals, feathers and clouds that have a somewhat twirly appearance.
External characteristics, or blemishes, are confined to the surface of a diamond and most often occur after a diamond’s formation; during the cutting, mounting, and wearing of a polished diamond. Blemishes usually only affect the clarity grade in the top two categories (Flawless and Internally Flawless), whereas inclusions affect all grades. Flawless diamonds are very rare – so rare, that it’s possible for a jeweler to spend a lifetime in the industry without ever seeing one.
Types of Blemishes: (surface characteristics)
- Polish lines- fine parallel grooves and ridges left by polishing; they can occur on any facet but do not cross facet junctions; transparent or white.
- Burn– caused by excessive heat on the polishing wheel during cutting.
- Grain boundaries– occur when the grains of two simultaneously forming crystals meet. When this happens, the direction that crystal is growing in essentially shifts.
- Natural– a part of the rough diamond which was left untouched during the polishing process, they are usually found at the girdle.
- Extra Facet- A facet that’s not required by the cutting style, placed without regard for the diamond’s symmetry; most often found near the girdle.
- Lizard Skin- Wavy or bumpy area on the surface of a polished diamond.
- Cavity- a small hole in the stone’s surface usually created during the polishing process when an internal inclusion like a crystal or knot falls out of its pocket.
- Scratch- a thin, dull, white line across the diamond’s surface; shows no apparent depth at 10X.
- Nick- A small notch on a facet junction with no readily apparent depth at 10X, usually along the girdle edge or at the culet.
- Abrasion- A series of minute nicks along the facet junctions of a fashioned diamond; gives the edges a white or fuzzy appearance.
- Pit- a small opening that looks like a tiny white dot.
- Chip– a small opening on the surface of a diamond often found near the edges or facet junctions.
What is a Plotting Diagram?
A plotting diagram is a map of a diamond’s clarity characteristics. The diagram is an important part of the GIA diamond grading report, as it maps out where the blemishes are on a diamond’s surface and where the inclusions are within the diamond. With the plotting diagram you can identify diamonds of the same clarity grade from one another. Just like a fingerprint, every diamond’s internal features and external characteristics are unique.
When plotting the diamond, each category of clarity characteristic is assigned a color:
- Red: indicates most inclusions
- Red and green: when used together indicate cavities, indented naturals, knots, etch channels and laser drill-holes
- Green: indicates naturals
- Black: indicates extra facets
The colors and symbols will help you identify each type of characteristic and the plotting diagram will help you locate them on your diamond.
That concludes our blog post on Clarity for today, but we will be referring to things from this blog post as we continue to move forward with your diamond education. Come back in 2 weeks to learn about a diamonds COLOR!
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