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GCAL CLARITY GRADING


In this section:


The Clarity Grading Environment

Grading a diamond in a laboratory environment is the ideal way to examine and analyze a diamond. The most important advantage to the professional diamond grader is the ability to maintain a perfectly clean object diamond. Field grading presents a difficult task of usually examining the diamond while in a mounting. There are many cleaning solutions and devices like compressed air, dental water picks, and needle-like probes to help the grader. Beyond a clean diamond, other challenges like prongs and bezels, baskets and under-galleries challenge the optimum viewing angles of the grader. We are presenting grading procedures and principals we use every day in the laboratory, and yes, there are many times we are grading diamonds in mountings.
The importance here is to refresh the memories of our clients and colleagues of the definitions and grading tips for more consistent grading and grading expectations from legitimate labs. There are two distinct methodologies for clarity grading. They are dry grading and water grading. The most common is dry grading as described below.

Clarity Grading Procedure

• Clean the diamond. Never touch the diamond with your fingers while grading.
• With tweezers, hold the diamond in the face up position and examine under 10x microscope. If there are inclusions present, determine if they are VS1 and above, or VS2 and below.
• If it is VS1 or above, turn the stone over and check the culet area. Inclusions are commonly missed in this area. Then, hold the diamond in the table-to-culet position and examine the pavilion for inclusions while slowly spinning the diamond. Look through the pavilion 2-3 times, and then once again through the crown.
• It is more accurate to keep the diamond stationary (in tweezers or stone holders) and use the focus knob to look in and out of the diamond. The focus knob is much more delicate then your hands moving the diamond. Always be aware of the area coming into view as you concentrate on the area in front of you. And always be aware of the areas that have a black background. If it is VS2 or below, examine the pavilion for surface reaching inclusions.
• Once inclusions have been found in the microscope, examine the diamond under a 10x loupe and make a final grading decision.
• Always consider these 5 factors when establishing a clarity grade:
  o Size of Inclusion(s)
  o Number of Inclusion(s)
  o Position of Inclusion(s)
  o Nature of Inclusion(s)
  o Color/relief of Inclusion(s)

Clarity Grading Tips

The '4-Position' Method for Deciding Borderline Clarity Calls

• After viewing the diamond in the microscope for all clarity characteristics, the grader/appraiser will have an opinion of what the grade will be through the microscope view. This view is just used as a reference.
• The final grade will ALWAYS be determined by the way the diamond appears through a 10 power loupe.
• Using a 10x loupe, view the grade setting inclusions, in four positions. Twelve o'clock, six o'clock, three o'clock and nine o'clock.
• Make four clarity decisions, one for each clock position.
• Like in baseball, a tie goes to the runner, meaning a tie goes to the benefit of doubt. The lower grade needs to be the majority look, not an even split. For example, if you see SI2 in two directions and I1 in two directions, then the final grade is SI2.

The 'Theoretical Grading' Method

• After locating all the grade setting inclusions, make the call that you think is correct. Then look at the grade setting inclusions again and mentally change what you are seeing. Then consider if your grade decision still makes sense.
• For example, mentally move the crystal from the center of the diamond to the edge, or change a crystal from dark to light, or eliminate some of the inclusions that contributed to the grade.
• Consider how you would grade the clarity with the inclusions in a new location, etc. Can you justify your original decision?\
How to Grade Transparent Feathers and Knots
• First, make a determination as to the clarity grade of the feather's size as if size was the only factor, and disregard where it is.
• Next view the feather in a face up position, and make a clarity decision based only on the face up view. Forget that it is a feather; just view it as to how bright and how much of it you can see.
• If you think size is SI2 and the visibility is SI1 or SI2, than the final grade is SI2.
• If you think size is SI2 and the visibility is VS2 or higher than the grade will be SI1, but never more than one grade higher than the nature grade.
• This will work with all feathers up to VVS2.

How to Grade High Clarities (VVS2 and better)

• Always be careful to check the culet area for inclusions. Hold diamond girdle to girdle and inspect culet area from the pavilion side.
• All possible grade setting inclusions have to be callable with a 10 power loupe. A pinpoint visible with the microscope at 10x but not visible with a 10x loupe is considered to be Internally Flawless.
• It does not matter how many pinpoints are callable at 10x through the pavilion, for the grade to still be VVS1.
• Diamond with naturals or extra facets anywhere on the diamond can still receive a grade of Internally Flawless. If a natural is indented, the diamond is graded VVS1 or below.
• White lines, scratches or pits are often incorrectly called grade setting inclusions that lower a grade below Internally Flawless. The key making the correct decision is to view the depth or lack of depth from the opposite side of the blemish at 10 power.
• The most difficult and misunderstood high clarity characteristic is internal graining.

Types of Graining

Graining is caused by distortions in the atomic crystal structure. Graining is commonly overlooked and misunderstood. It is often the grade setting clarity characteristic in VVS quality diamonds. Remember, to be considered graining must be loupe-able as it is seen in the microscope. Here are some types of graining:
• Reflective graining looks like a frozen sheet of saran wrap extending into the diamond and is associated with surface grain lines.
• Surface graining is the easiest to see but will only lower the grade to IF.
• Colored graining, most commonly brown, pink or green, looks like colored lines running through the diamond and is best seen when viewed in diffuse white light.
• Whitish graining is the most difficult to define, but can be described as white lines, white bands, smoke, rain, or shimmering lines. It usually disappears easily and is best seen at exaggerated viewing angles.

Water Grading

Water grading is a technique that some graders prefer because it quickly removes surface dust and assists looking into the diamond. To water grade, add a few drops of liquid Joy detergent to a jar of water and use a brush applicator. The wet brush is used in place of a pointer to remove dust and rotate the diamond in the stone holders. If you decide to give water grading a try, here are a few things to remember:
• Water grading is most efficient for low clarities, but difficult with mounted diamonds
• The drying water leaves a film that can interfere with accurately seeing the diamond
• It is hard to loupe when using water
• High clarity inclusions and polish features are missed when water grading.
• Water grading distorts facet shapes when judging symmetry


 Video: Watch How Diamonds are Clarity Graded at GCAL


CLARITY GRADE DESCRIPTIONS

The following are examples of the types of inclusions and comments about each clarity grade.


Feather

Feather

Crystals

Knot

Twinning Wisps

Chips

Surface Graining

Reflective Graining

Brown Graining

Drag Lines

Polish Lines

Burn Marks

Burn Marks

Flawless

No internal or external Inclusions at 10 power
No blemishes, surface graining, extra facets, polish lines, scratches or naturals at 10 power
Naturals totally confined to the girdle can be Flawless.
Excellent polish does not guarantee Flawless but a Flawless diamond has to have excellent polish.

Internally Flawless

No internal or external inclusions at 10 power
Any polish grade, symmetry grade, color grade or type of proportion can obtain an IF grade.
Extra facets, naturals, surface grain lines, polish lines, scratches, abrasions, and pits are acceptable

VVS1

• Internal inclusions such as: Pinpoints, clouds, needles, or callable internal graining only visible through the pavilion.
• Surface reaching inclusions such as: Bruises, chips, feathers and indented naturals not visible face up.
• Bearding on pavilion side.

VVS2

• Inclusions loupable face up, such as: Pinpoints, clouds, needles, callable internal graining
• Surface reaching inclusions, such as: Bruises, chips, feathers and indented naturals that are loupable face up
• Diamond should be louped without exaggerated tilting.

VS1

• Small to very small crystals of a limited number.
• Small clouds of a limited number. Density matters.
• Small to medium needles of a limited number.
• Small feathers of a limited number.
• Medium sized feathers slightly visible face up.
• Medium sized bruises of a limited number.
• Small chips of a limited number.
• Small indented naturals around the girdle.
• Usually only white inclusions.
• Numerous reflecting pinpoints

VS2

• Small crystals numbering no more than three or four.
• Medium size individual crystals.
• Medium size dense clouds.
• Light clouds throughout, visible face up.
• Slightly large, thicker needles of a limited number.
• Medium sized feathers visible face up. Orientation matters.
• Large feathers not visible face up nearest to the girdle edge.
• Slightly large sized bruises of a limited number.
• Medium sized chips of a limited number.
• Medium sized indented naturals around the girdle.
• Small black inclusions of a limited number.

SI1

• Medium to slightly large crystals, feathers and needles.
• Hazy diamonds due to clouds or whitish graining.
• Slightly large cavities, chips and indented naturals.
• Numerous VS2 sized inclusions.
• Numerous reflections of VS2 sized inclusions
• Very slightly eye-visible after louping and positioning inclusion in brightest location.

SI2

• Large feathers, crystals, black inclusions, numerous twinning wisps, large knots, and large dense clouds
• Often look 'busy' with the loupe but when viewed with the naked eye only some/none of the inclusions are noticeable
• Eye visibility varies with observer's experience, size of diamond, lighting, familiarity with inclusion location, etc.
• Most difficult of all clarity decisions

I1

• Inclusions are easily visible to the unaided eye.
• Inclusions may affect transparency, brilliance and possibly durability

I2

• Very easy to see with the unaided eye.
• Transparency and brilliance is significantly diminished.
• Inclusions may impact the durability of the diamond.
• Approximately ¼ to ½ of the diamond lacks transparency

I3

• Extremely visible to unaided eye
• Inclusions may significantly impact the durability of the diamond
• More than ½ of the diamond lacks transparency

FREQUENTLY ASKED QUESTIONS

What exactly does clarity mean as it relates to a diamond?

Few diamonds are perfect. Given their enormously violent birthing process in volcanoes millions of years ago, most diamonds have tiny remnants of their beginning or intruder minerals inside them. Thankfully, most of these inclusions, as they're called, are hidden from sight. It takes magnification to see them.

A clarity grade is an evaluation of the degree to which a diamond is free of blemishes and inclusions. Inclusions can be thought of as natural birthmarks on a diamond. Since no two diamonds have exactly the same inclusions, this property can also be described as an identifying characteristic.

How are diamonds clarity graded?

Grading diamonds for clarity is a process of hunting down microscopic imperfections and rating them for difficulty of discovery. The more difficult it is to find inclusions under 10x magnification— using a binocular microscope— the higher the clarity grade. Once these specks are found, their number, size and location all play a role in deciding the clarity grade.

Gemologists use an 11-grade scale— from FL (flawless) to I3 (very noticeable to the naked eye) - to grade for clarity. Each grade down represents increased ease of detection. In short, grades stand for degrees of visibility.

Diamonds with no discoverable imperfections under 10x magnification earn a FL (flawless rating). If there is an oh-so-slight surface imperfection, it gets an IF (internally flawless) grade.

Next comes the VVS (very, very slightly included) grades, in which there are two, and the difference between them has to do with whether an inclusion is extremely, or merely very difficult, to see.

Once the difficulty factor is reduced, diamonds receive grades of either VS 1-2 (very slightly) or SI 1-2 (slightly) included. If this sounds like gemological knit-picking, keep in mind that degrees of perceptibility can make enormous value differences.

Finally, there comes a point at which inclusions become noticeable to the naked eye. Diamonds with visible inclusions receive one of three I (included) grades.

When buying diamonds, especially ones that have been mounted, always ask for a diamond certificate. Some manufacturers and retailers hide visible inclusions under prongs. You want a diamond that has no hidden surprises.

Should I be concerned that a diamond with inclusions is a weaker diamond?

No, except with diamonds graded I2 or I3, in which case durability becomes a concern. Diamonds graded I1 or higher are not 'weakened' by their inclusions.

Diamonds are not indestructible. Diamonds are the hardest natural material and can only be scratched by another diamond, but they can break if struck too hard. Take off your jewelry when doing any hard labor.

Is it worth the money to buy a diamond with higher clarity?

This is a personal decision. If perfection is your style, then consider a diamond graded VS1 or higher. If you want a diamond at a good value without any inclusions visible under normal conditions, then consider a diamond graded VS2, SI1 or SI2. If you want big flash for little cash, then consider a diamond graded I1, I2 or I3.

At what point can inclusions be seen with the naked eye?

Several factors influence which inclusions you can see with your naked eye – the quality of your vision, the lighting, the angle of view, the cut of the diamond. Generally speaking, diamonds graded SI1 and higher do not have eye visible inclusions. Diamonds graded SI2 and I1 may or may not have inclusions that are visible without magnification. I2 and I3 diamonds have visible inclusions that even a bat can see.

How do I know my diamond was graded correctly?

Make sure your diamond comes with a Grading certificate from a respected gemological laboratory, such as GCAL. GCAL is an independent laboratory, not affiliated with any jewelers, and has the consumers' best interests in mind.

Clarity grading is a subjective scientific procedure that depends on the skill and experience of the grader and reasonable variances are possible, but every effort is made to eliminate bias. GCAL utilizes consensus grading methodology and an exceptional quality control procedure to assure the most accurate, objective and consistent grading possible. Before GCAL gives a diamond its quality grades, each stone is individually examined by two experts and verified by a third senior expert. Every diamond is weighed, measured, examined, tested and photographed several times before a certificate is issued.

How does clarity affect value?

Minute, minor, noticeable, obvious...
These terms are used to describe the visibility of inclusions within a diamond... under 10x magnification. And since most people aren't showing off their jewelry under jeweler's loupe, consider what you can see with you unaided eye.

Diamonds graded VS2 and higher will all look the same to the naked eye (all other factors being the same). Diamonds graded SI1, SI2 and I1 have inclusions that you may be able to see without magnification. Within this clarity range, it is important for you to look and see for yourself because inclusions are as unique as snowflakes and everyone's vision. Diamonds graded I2 and I3 have large inclusions that are easy to see and can affect the durability, so these should be avoided.

As with the other quality factors, value differences between each grade are most significant in higher quality diamonds. All other factors being equal, each clarity grade increment has a 20-25% price difference in a 1.00ct D-color diamond, whereas each clarity grade increment has a 10-15% price difference in a 1.00ct I-color diamond.


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