When appraising a diamond, determining its clarity grade is a very important step. The presence or absence of stains on a diamond will greatly change its value. However, stains are not always considered harmful. For example, diamond-cutters look at the spots on a piece of diamond to identify a piece of diamond that does not have a definite crystal shape and surface features. Diamond clarity is measured with a scale. So what is the diamond clarity scale?
The diamond clarity scale consists of 8 levels. Each level is assigned a letter. These letters are, clearest to least clear, F, IF, VVS1, VVS2, VS1, VS2, SI1, and SI2. Diamonds having an F clarity level have the highest clarity on the diamond clarity scale. Similarly, SI2 level diamonds have the lowest clarity degree. Better clarity diamonds are more expensive than low clarity ones. Hence, clarity is an important criterion in diamond selection.
However, the spots on the diamond are of great help to jewelers in two ways. First, blotches distinguish diamonds from their ubiquitous imitations. Second, one diamond is distinguished from another by its distinctive spots. Therefore, when describing stains to customers, it would be more accurate to say “differential features” rather than “imperfections” or “stains”. Using a microscope such as the IGIscope gives the jeweler the opportunity to show their clients how small specks look and how interesting and beautiful they look on certain stones.
Getting an honest and knowledgeable presentation from the jeweler about the clarity of the diamond will both reduce the customer’s suspicion and increase sales. This section will be about the introduction of the most common internal and external properties of diamonds. The blemishes found in diamonds are unlimited. Almost every day, diamond graders at IGS labs look at blemishes and other characteristics they’ve never seen before.
IGI Diamond Clarity Grading System
For many years, manufacturers and wholesalers used their own clarity grading systems and terminology. There was a great diversity among them and it would be impossible to describe them all here. The highest rank, though by different names, was more or less the same for almost everyone. To avoid these problems, the international clarity rating system was adopted.
There were differences until about 15-20 years before the adoption of this system. This international clarity system is now used by many laboratories around the world. The grades that the IGI lab uses for diamond clarity are: completely spotless inside, two categories, very, very small spots (VVS), very small spots (VS), small spots (SI), and three categories of piques (P).
- Unblemished interior (IF)
When magnified 10x under a microscope, a machined diamond that does not contain any internal defects is classified as an internally unblemished diamond. Natural tracks, extra surfaces, etc. Minor marks such as a needle tip may not be visible at 10x magnification, but can be seen at a higher magnification. So if a diamond has a pinpoint stain, you can only see it at 15x magnification, at 10x magnification this stain will disappear, you can put this diamond in the IF category.
- Very very small spots (VVS1-VVS2)
This category includes diamonds with very small blemishes that even the most expert diamond smith will have trouble detecting at 10x magnification. One or two small pinheads set on the table or other part of the diamond, a small hairline-like feather, incurving lines are excellent examples of the VVS1 grade. Many VVS grades are presented like IF-grade diamonds with no ulterior motives because these tiny specks are really hard to spot. Depending on how they affect diamonds, minor nicks, internal veining, small bruises, bearded belts are sufficient to place a diamond in the VVS1 or VVS2 category.
- Very small spots (VS1-VS2)
Although the spots that make up this category are easier to detect at 10x magnification, they are defined as very small spots when viewed with a diamond loupe or a microscope. To put a diamond in the VS category, small clouds, grouped pinpoint specks, small additional crystals, or small hairs must appear on that diamond. These properties affect either the beauty or durability of the diamond.
- Small spots (SI1- SI2)
This category includes diamonds with minor imperfections that are noticeable or easily spotted at 10x magnification. Small spots that may be in the S1 category are clouds, feathers, and additional crystals. S1 stains are impossible to detect when viewed from the table side with the naked eye, they are not visible, but when S2 stains are viewed with the naked eye from the tableside, it is very difficult but possible to find the stains.
- Pique (P1-P2-P3)
Diamonds in these categories have spots that are very visible when viewed at 10x magnification and are also visible to the naked eye when viewed from the tabletop. The possibility that some of these stains may affect the life, transparency, and brilliance of the diamond creates a problem. The difference between P1, P2, and P3 is a matter of degree. P3 is the last category and the blemishes of diamonds in this group affect the transparency of the diamond and are very easy to detect even with the naked eye. Grade P3 they are most commonly classified as industrial diamonds. It all depends on the gem qualities of the time and industrial demand. Typical spots in this category are large pits, large hairs, and large dark additional crystals.
There are some important factors to consider when assessing the clarity grade of a diamond. In your assessment, you will have to outline the color, position, number, size, and nature of the blemishes rather than considering them individually. In particularly sensitive cases, make your assessment by looking at the comprehensive summary of the properties of diamonds that you magnify 10x.
The color, position, number, size, and nature of the blemishes must be considered together, although each will affect the degree of clarity of a diamond. The size of a blemish will undoubtedly affect the degree of clarity, but if many similar small blemishes are found on the tabletop or near the belt, they are between categories VS1 and VS2. will make the difference. So the position is equally important as size.
The number of spots is another factor to consider. E.g; If a diamond has a group of small pinpoint spots located in a less visible area, it will still fall into the VVS2 category. The color of a stain is another important factor. A dark stain will be easier to see than a colorless one. This again depends on the size of the blot, as a small black blob is less likely to show up than a large white blob. A hair or large slit from the surface to the inside of the diamond will reduce the clarity of the diamond because these hairs or crevices can expand further in the diamond by mechanical means such as pressure or impact.
How to Examine the Clarity of a Diamond
There is no single procedure for how to start examining the clarity of a diamond. You can use any technique to locate the different blemishes present in a diamond. As long as you find the blemishes and get the right result for that diamond, use the method that works best for you. As said earlier, there is no specific procedure for how to start examining a diamond, but there is a sensible way to start. The prone position is the most important position for determining the clarity ratio.
Therefore, the most logical procedure would be to examine the diamond perpendicularly from the table and crown surfaces. If you can’t see any blemishes at first glance, the clarity of the diamond is very good. When you have finished examining the diamond from the crown, turn the stone and examine it from the cone. This is without a doubt the best way to locate the smallest blemish that cannot be seen from the crown.
To examine a diamond from the cone, place the diamond table-side down on the cleaning cloth. Take your tweezers and remove the stone. Move the diamond to a horizontal position. Do not apply too much pressure when holding the stone with tweezers as you may damage the stone. By holding the stone in this position, you can remove natural marks, extra surfaces, hairline-like hairs, nicks, etc. You can see the smallest blemishes such as pins, bruises, clouds, feathers in the belt area and inside the diamond. By carefully rolling it on a non-slippery flat surface, you can rotate the stone so you can see the entire arch area of the diamond.
One of the biggest problems for diamond professionals is the difference between dirt, blemishes, or marks. The most effective way to tell them apart is to take a needle and touch the scar. If the “stain” moves, it is obvious that it is not part of the diamond. Another way is to watch either side of the face in reflected light. Turn your diamond towards the light source and inspect the tabletop and other surfaces. If the light is reflected directly onto the diamond, the surface will not appear transparent and surface marks will be reflected. Thus, if there is something on the surface of the diamond, it will be exposed.
If the mark looks encircled, it is located inside the stone, which means there is a stain. Reflections also cause certain problems for the rater. Diamond has the ability to reflect a single stain over and over. To find out exactly how many spots there are, it will be enough to turn the diamond to another position. In addition, it is almost impossible to detect two or more spots that are the same and placed side by side in a diamond.
On the other hand, another form of reflection that creates problems is the reflection from where the tweezers touch the diamond. E.g; When the diamond is held in the tabletop position, the tweezers will touch the belt part and its reflection will cover this area. Small spots can easily be overlooked in this area due to breakage.
When we want to grade a diamond for clarity with a diamond loupe, it is very important to properly illuminate the diamond. Therefore, it is recommended to use a “daylight type” lamp. Hold the diamond at the tip of the lamp so that the minimum amount of light reflects from the crown and maximum light enters from the pavilion. There are other methods for lighting up a diamond. Put the light behind the diamond, but this method will leave the pavilion in the dark when the diamond is viewed from the tableside.
Another method is to put the light on the side of the diamond, but this time too much light will be reflected from the crown surfaces, making it difficult to see inside the stone. These last two methods are less effective and therefore of little use. The best form of lighting is the direct lighting system or dark-field lighting system known as the IGIscope. With the IGIscope, maximum light enters the cone so that reflections from the crown surfaces are minimal and the inner features of the diamond are better visible.
Analyzing Diamond Clarity in Terms of Internal and External Properties
In terms of clarity, a diamond is examined in two steps. First, to find and classify blemishes and marks, and second, to evaluate the effect on the diamond’s clarity ratio. To give a clear degree of clarity, it is first to be able to find and identify the different blemishes present in a diamond, which takes practice and experience, and secondly, to understand the different standards of clarity. These skills are not easily learned, they take time. Before starting to evaluate the stones, it is absolutely necessary to take some precautions.
Diamonds have a great affinity for dust and oil, so the diamond must be very well cleaned before it can be graded for clarity. You have to be very careful when touching a diamond with your fingers because some oil can accumulate on the diamond no matter how clean your hands are. So the rule of thumb when evaluating a diamond is to clean it well and never touch it with our fingers. In many cases, single diamonds are cleaned with lint-free cloths. This fabric has two sides: the hard side and the soft side. Fold the fabric with the soft side out. Put the diamond inside the fabric. Take the diamond between your thumb and forefinger, and rub it together with the fabric.
For most diamonds, this method is sufficient to clean them perfectly, but sometimes a toothbrush with a dab of liquid detergent or oil-free isopropyl alcohol may be required to remove dirt. After this, a final cleaning with the lint-free cloth will make the diamond perfect. Diamonds in old rings are always very dirty and a trace of metal may be stuck to the stone. Two methods are used to remove this dirt: The first method is to boil the diamonds in sulfuric acid, and the second method is to boil the diamonds in a stronger liquid detergent.
ATTENTION: These methods can only be applied to single diamonds. In the first method, a very dangerous chemical substance is used. To apply this method, certain conditions are required: you must buy a special tool and carefully follow its instructions. You will also need a well-ventilated environment, as fumes can damage your lungs or skin. In the second method, strong liquid detergents are used.
Place the apple in a heatproof glass container, covered completely with undiluted liquid detergent. Heat on high heat until boiling. Let the solution cool and then rinse the apple with warm water. Other methods require steam and ultrasonic cleaners but are not effective enough and IGI does not recommend using either of these two methods.
Diamond Clarity Scale and Diamond Diagrams
In a diagram, when marking the characteristics of a diamond, the most important thing is to keep the stone steady. To do this, hold the diamond between the diamond tongs or tweezers, this way it will be easier to locate the different spots. You have to think of your diamond like a clock: divide it into quarter circles like 12 o’clock, three o’clock, 6 o’clock, and 9 o’clock. First, look at the diamond in the tabletop position. E.g; A stain formed on the star’s surface at 2 o’clock will be marked in the same place on the special diamond diagram with the help of a microscope.
The spots should be lightly marked and the proportion, size, and shape of the spot should be reproduced in the same way as on a diamond. Don’t try to make a diamond in the VVS category look like a VS. Remember that another professional looking at your chart should be able to correctly read the degree of clarity from the markings you have made. The diagram should show all the features of the diamond, be it in the crown, the cone, the belt, exactly where they are located.
The reason for the idea to show the properties of a diamond in a diagram is to keep a record that would allow a diamond expert to identify a diamond because no two diamonds will have the same internal and external characteristics. The degree of clarity given to a diamond and its display in a diagram reveal what condition the diamond was in at the time of marking. If there is any damage to the diamond afterward, this diagram will be proof of the original condition of the diamond for the owner. The diagram supports the degree of clarity given to the diamond.
Different colored inks are used to distinguish between interior and exterior features. Internal features are shown in red and external features are shown in green. Sometimes a special black ink is used to more easily inspect a diamond marked in the VVS category. Marking is done under a microscope and then the stone is reexamined with a diamond loupe. The symbols used for marking are listed below:
- Extra surface EF
- Notch NK
- Natural N
- Scratch S
- Abrasion Abr
- Polishing lines Pl
- Outer curling lines Ext
- Feather Ftr
- Node K
- Needle tip PP
- Needle tip assembly GPP
- Additional crystal InX
- Dark additional crystal DinX
- Cloud Cld
- Inner curved lines T
- Bearded belt BG
- Hair-like feather HL
- Laser hole LDH
- Crash mark PM
- Pit CV
Types of Stains That Affect the Diamond Clarity Scale
A slit is a crack formed in the direction parallel to the crystalline cleft planes. These planes are related to the crystal structure of the stones. A crevice crack affects a diamond’s clarity rate more than other types of cracks because if the stone is handled more, the crack can expand and spread. In the case of such a crack, it should be properly explained to the consumer.
A crack is any fracture that does not occur in the direction parallel to the cleft planes. Cracks often appear uneven or crooked. A feather is a slit or a crack in a discrete plane that, when viewed at right angles, gives the appearance of a feather. A feather that appears white is commercially called a “gletz”. The facial hairline looks like a line at first glance but grows into a diamond. Since the word “feather” is a more positive word than slit or crack, it may be better to use this word when selling or rating a diamond.
A crystal in the inner part of the diamond, which is shaped differently than the crystal it is in, is called a knot and is encountered while shaping the diamond. The knots stand out as small, embossed surfaces after polishing.
The cloud is formed as tiny fragments of very fine additional crystals. Usually, they have a hazy and blurry appearance and when found in a large area, they affect the transparency of the diamond, hence its beauty.
- Additional crystals
The different minerals that form within a diamond are identified and identified, and these are called additional crystals. The most common additional crystal in a diamond is another diamond. Other inclusions found in diamonds are crystals, olivine, granite, tourmaline, and spinel. Although most of the additional crystals are colorless, they vary in color, shape, and size. An additional crystal of any color is called a “dark additional crystal”.
- Needle tip, point
The needle tip is a very tiny additional crystal that appears as a small white speck when magnified at 10x magnification. Pinpoint crystals can be found singly or in groups. The pinpoint crystals that are gathered together are called the pinpoint group. A solitary pinpoint crystal is very difficult to detect at 10x magnification due to its size (a few microns).
- Laser hole
A laser hole is a small artificial hole (.02-.04millimeters) made with a laser that will give the impression of a dark additional crystal in a diamond. This hole is made with a focused laser beam, which emits very intense heat. After the dark hole is drilled, it is bleached with special acids such as hydrofluoric or perchloric acid. With this method, the dark additional crystal is made colorless or white, thereby increasing the sellability rate of the diamond. Because it has improved the appearance of the diamond, it is perceived as a positive value in a sense. On the other hand, an additional crystal may be added to the diamond in a tubular form, and this additional crystal may reduce the clarity of the diamond. IGI always recommends that the customer be notified if the diamond has a laser hole.
- Impact marks or bruises
It is defined as hard bumps, bruises, or impact marks that can occur as a result of normal wear as you use a diamond. They appear as white marks on the surface of a polished diamond and can vary in size from large to small. Berets are considered in the group of internal features because they always have a slight penetration into the diamond.
- Bearded belt
If the diamond is rotated too quickly while shaping a diamond, tiny hair-like cracks will propagate from the belt into the diamond. These are perceived as external features and are called bearded belts. These cracks are usually not very deep into the interior of a diamond.
- Veining or vascular lines
The veining is caused by plastic deformation that occurs in the structure of a diamond. They appear as parallel lines and can occur in slit planes and on different diagonal surfaces. The fact that they occur on these surfaces allows us to easily distinguish them from other lines that occur during polishing.
- Curling lines
They are lines in high relief that are parallel to each other, caused by occasional interruptions in the growth of a diamond.