# The Four C'S

First off, let’s start with reading about the basics. Diamonds are weighed in carats. What is Carat? Carat is the unit of measurement of a diamond’s weight. Ct is the abbreviation standing for Carat Weight. Why must we measure diamonds in carats? The Fourth General Conference on Weights and Measures accepted the metric carat (.20gram) as a unit of weight in the early year of 1907.

Metric carat equals 0.20 gram as one carat equals 0.20 gram

Carat Weight is determined in units of carats on a diamond scale. Learning Carat Weight is pretty easy when you know about the points that are involved. Points are most commonly referred to diamonds under one carat. For example：

－ 0.10ct equals 10 points or a10pointer

－ 0.20ct equals 20points or a 20pointer

－ 0.30ct equals 30points or a 30pointer

－ 0.40ct equals 40points or a 40pointer

and so on.

Only when the 3rd number is a 9, the diamonds’ weight is rounded up to the next decimal point. So for example;

－ 0.995ct is rounded to 0.99ct

－ 0.996ct is rounded to 0.99ct

－ 0.997ct is rounded to 0.99ct

－ 0.998ct is rounded to 0.99ct

－ 0.999ct is rounded to 1.00ct

Now, you may hear the words “Magic Numbers” frequently when searching about diamonds. This term is described as diamond sizes that are flat. Why to avoid flat numbers?  When a diamond reaches certain flat numbers, its price takes a sudden increase, around 20-30%, from a diamond that is 1 point below it. Eg. A 0.49ct and a 0.50ct. The reason why you find so many flat number carat diamonds in the  market is because diamond cutters prefer to sell a diamond of inferior quality and make more money by cutting out a flat carat size diamond as compared to say 0.99ct of a higher quality but lose almost 20% in value. Hence, it is difficult to find well cut diamonds of high carat sizes close to the flat carat sizes. The amount of weight loss is just not worth economically for diamond cutters.

Magic number weights such as 0.50ct, 0.70cr, 1.00ct, etc. are a lot more expensive than premium carat weights such as 0.89ct, 0.99ct and 1.99ct despite a slight different of 0.01ct. This is because the price increases drastically when it reaches the next carat weight pricing bracket. For example, diamonds are priced in different pricing groups, such as 0.50-0.69ct, 0.70-0.89ct, etc. Hence, a 0.69 and a 0.70ct would have a price difference of over a thousand dollars, despite being only a 0.01ct difference, whereas a 0.70 and 0.71ct will only have about a \$100 difference as they belong within the same pricing bracket.

There are people in the marketplace who determine diamond prices based on its qualities, supply and demand. These reports are published in the marketplace. These pricing reports are categorized in weight. Some examples of these magic numbers in weight are;

－ 0.30ct

－ 0.40ct

－ 0.50ct

－ 0.70ct

－ 0.90ct

－ 1.00ct

－ 1.50ct

after that last carat size, the magic number in weight increases every half carat.

Carat weight CAN affect a diamond’s value. It’s pretty simple. The larger the diamond, the more expensive it’ll be. The quality of a diamond ranges the price per carat of a diamond. Since large diamonds are rarer, the price increases as the carat weight increases.

Have a look at how different carat weights look on a finger.

The diamond’s size is NOT the same as the diamond’s carat weight. It is very possible to find two diamonds of 1.00ct and to have one that looks 25% smaller than the other. This is due to the way that the diamond is being cut. A diamond cut with a shallow depth would make the diamond appear larger in size while a diamond that is cut deeper will appear much smaller in size. In very extreme scenarios, it is possible to find a 1.00ct diamond equal to a size of a 0.40ct diamond.

A good example is the video below, showing the importance of Cut over Carat, where a better Cut diamond can look bigger against another diamond with the same carat weight.

Following Carat Weight, we learn about Clarity. The less inclusions a diamond has, the more expensive it will be. Clarity refers to the possible existence of internal and external inclusions of a diamond. This identifies the inclusion characteristics within and on the diamond.

GIA’s scale of clarity grading is represented as

No imperfections - FL or IF

(Flawless - no blemishes or internal inclusions under 10x magnification)

(Internally Flawless meaning no internal inclusions under 10x magnification)

Minute imperfections -VVS (VVS1, VVS2)

(VVS1 - extremely  difficult to see inclusions under 10x magnification)

(VVS2 - very difficult to see inclusions under 10x magnification)

Minor imperfections - VS (VS1, VS2)

(VS1 - difficult to see inclusions under 10x magnification)

(VS2 - somewhat easy to see inclusions under 10x magnification)

Noticeable imperfections - SI (SI1, SI2)

(SI1 - easy to see inclusions under 10x magnification)

(SI2 - very easy to see inclusions under 10x magnification)

Obvious imperfections -I (I1, I2, I3)

(I1, I2, I3 – inclusions are obvious under 10x magnification and affects the diamond’s durability, brilliance and overall appearance.)

(Some diamond labs use the term "Pique" or pronounced as “PeeKay” using the abbreviations P1, P2, and P3, rather

than I1, I2, and I3.)

AGS’s scale of clarity grading is represented as

－ AGS 0 = GIA FL and IF

－ AGS 1 and 2 = GIA VVS1 and VVS2

－ AGS 3 and 4 = GIA VS1 and VS2

－ AGS 5 and 6 = GIA SI1 and SI2

－ AGS 7,8,9,10 = GIA I1, I2, and I3

Clarity Characteristics can be Internal inclusions or external inclusions. The Size of the Inclusion, Quantity of Inclusions, Type of the Inclusion, Color/Relief(reflectivity), and the Placement of the Inclusion, determine the Clarity Grade. While diamonds with High Clarity are always in demand as they stand for purity to most, diamonds with Medium Clarity (VVS1 to VS2) can be as great as Flawless diamonds as no one can see the difference.

You should use both Darkfield Illumination and Overhead Lighting when viewing diamonds. The Darkfield Illumination is very important when determining a diamond’s clarity grade. This is a microscope that takes pictures of diamonds when it is placed under high intensity light with the diamond sitting on a black base. This light focuses on the pavilion facets, and reveals the inclusions of the interior on the diamond. When using the Darkfield Illumination microscope, the inclusions are clearly shown due to high intensity light, but this is not how the diamond will look in just Overhead Lighting.

A diamond is Eye-Clean when its inclusions cannot be seen in a ‘face up’ position and viewed 6-12 inches away from the eye. It is possible to see imperfections with the naked eye on a lower clarity grade such as SI when turned face down. Note that this view can innaccurately represent the diamond’s clarity.

FL-VS2 (FL being Flawless, VS2 being somewhat easily noticeable) are considered the ideal clarity. Coming after FL, VVS diamonds are next in the clarity grading scale. VVS stands for very very small inclusions. These are the second-best grade but it is difficult to distinguish them from Flawless diamonds without an expert’s assessment on their inclusions. Some VVS inclusions include, small internal or external spots, a small crystal, a slightly rough facet edge, or one or two slightly larger cut faces. However, since Flawless diamonds are almost impossible to come across, VVS diamond’s in clarity hold the most high value. If you do have trouble choosing between a Flawless and a VVS diamond in clarity, just know that the cost is a big difference, and anyone that is seeking a high end diamond will usually take VVS diamonds for this reason. Following VVS diamond’s are VS diamonds. If you are financially looking for a more practical diamond, these are still considered one of the best diamonds, because even though you can see more inclusions than FL or VVS diamonds, they are less costly, and still outstanding diamonds!

From SI and there on, are known as the grades when you can spot out the inclusions with your naked eye. ‘I’ standing for Imperfect or Pique, means you can see inclusions on the diamond within 35cm without previously being informed where the inclusions are. VS1 and SI2 diamonds in Clarity are very different in quality, but they make look extremely identical to the naked eye, which is why it is important to have accurate and expert assessment of a diamond’s clarity.

• FL (Flawless):  No internal or external inclusions. There isn’t much to say about these except they are very rare and they are priced at IF cost.

• IF (Internally Flawless): No internal inclusions, but may have small, very unnoticeable external inclusions.

• VVS1 (Extremely Difficult): Very very slightly imperfect diamonds. They have very small inclusions which are extremely difficult to see. They can only be seen under 10x magnification, and even then, the inclusions are hard to spot! These inclusions are so small, they can be mistaken for little specks of dust or something irrelevant to the diamond at all! If the inclusions are a bothersome, they can be removed by a little re-polishing.

• VVS2 (Very Difficult): Experts can locate these under a 10x magnification. The inclusions are still very small, with maybe a few more minute flaws than VVS1, but it does not make VVS2 any less valuable than a VVS1 diamond.

• VS1 (Difficult): Very small inclusions, they have more small or large inclusions than VVS diamonds. These inclusions are still minor, and are usually not visible to the naked eye. Only skilled graders can locate them under 10x magnification.

• VS2 (Somewhat easy): Still very small inclusions but with more flaws than VS1 diamonds. This clarity grade is known as the cutoff grade for most buyers. Only a skilled grader can locate them under 10x magnification.

• SI1 (Easy): This clarity grade is still popular because it’s an eye clean diamond, and the price difference between a SI and a VS is hugeBuyers on a budge are more concerned about the price difference as they want a good price for a good looking diamond. The SI grade has easy to see inclusions under a 10x magnification and sometimes with the naked eye.

• SI2 (Very Easy): The inclusions in this grade get more noticeable to the naked eye, and under 10x magnification.

*SI3 Before the early 1990’s, SI3 was non existent. As these diamonds contain more flaws than the SI2 had, it was graded as “I” for Imperfect! The SI3 grade was made a grade for the reason that there are diamonds that have more inclusions than SI2 but not noticeable enough to be graded as Imperfect. SI3 is the grade that separates an easy to spot inclusion diamond from a diamond being considered Imperfect. However, the GIA and AGS still do not consider there being an SI3, they only use SI2 and I1.

• I1 to I3 (Imperfect): Diamonds with obvious inclusions in and on the stone are placed in this grade. They are both easy to see with the naked eye and jump out at you in the microscope. An eye visible feather, or crystal are common.

*I1 is different from I2 and I3. I3 has inclusions, but these inclusions do not affect the diamond’s overall brilliance if the diamond has a good cut grade. While this grade being classified is the lowest on the grading scale, this grade is the most common on price reports and people still buy them. If the inclusions are on the edges of the diamond, you can get prongs to cover up the blemishes on the diamond. However, severe inclusions on the edges can be a very bad thing.
• *I2 and I3These clarity grades containing large inclusions can diminish the diamond’s brilliance and affect its durability, hence why if you buy a diamond with inclusions on the edges of it, and use prongs to hide them, it can be a bad thing.

Internal Inclusions

Feather - This fissure is located within the diamond and can place a durability risk depending on how big it is and where it is located. These inclusions can be found from VVS’s to I’s. Usually if the feather is not on the girdle’s edge, does not connect to more feathers near the surface, or create an opening on the surface of the stone, it is not a durability risk. Feather inclusions can appear reflective, colored, white, or transparent.

*There are two types of feathers; straight and curvy. The straight feather( sometimes referred to ‘needle’) usually follows a cleavage plane. If the straight feather is glistening, or shining, it means that the feather has parted the diamond wide enough to let in air. Two feathers that are breaking the girdle at the interior of the diamond are a huge risk.

*Watch out for some enhanced diamonds, for they might have dangerous feathers that are hidden. Unless you know what has been done to the enhanced diamond, stay away from them. You can locate feathers by reading the clarity plot if you have a lab report. Thoroughly examine the diamond with a loupe from all angles to find feathers if your stone is not certified.

Pinpoint - Very small crystal, and it’s close to white in color. These inclusions can be found in any grade. The pinpoint is usually the inclusion that separates the VVS’s from IF grade.

Crystal - Mineral deposit found, either alone or in groups, in the inside of the diamond. It can be colored, or colorless but usually appears black in overhead lighting. Some diamonds may have large crystals that can be seen with the naked eye, and can affect the diamond’s clarity. Sometimes these crystals can resemble a diamond inside of the diamond.

Needle - An elongated inclusion. It is very similar to a feather, but it has no radiating lines. Needle inclusion is only visible to the naked eye if it has color or is very fine. Some are even given to the diamond to give it a special look.

Cloud - Known as a group of pinpoints.

Cavity - The surface of the diamond has an opening, as a result of a natural flaw in the rough stone.

Bruise - A chip in the diamond surface that may include root-like feathers radiating into the diamond

Bearding - Lines that occur during the cutting of the diamond.

Cleavage - Straight crack without any feathering

Internal Graining - Crystals that grew with a milky color, following faint lines or streaks, they can or can not be colored.

Knot - Included crystal that touches the surface of a polished diamond.

Laser Lines - Slightly noticeable trails left when lasers are used to remove dark inclusions

External Inclusions (blemishes)

Scratches - Fine lines usually around the surface of a diamond, possibly caused by cutting of the diamond. Deep scratches can be removed by enhancing the diamond. These can be curved or straight.

Fracture - Usually irregular in shape, causing the diamonds to look chipped. Basically, it’s a crack on the surface of the diamond.

Nicks - Diamonds are chipped at places such as the girdle or facet edge causing nicks. Can be fixed by adding more facets, just be warned that adding too many facets, can decrease a diamond’s brilliance.

Pits - Small holes/dots white in color on the surface of the diamond. Usually not noticeable to the naked eye.

Polish lines - Polishing a diamond can cause minute lines during the process.

Chip - A shallow nick in the surface of the diamond created during cutting.

Natural - The original surface of the diamond which has not been polished. This is actually considered a sign of good cutting practice.

Twinning Wisp - This line is noticeable inside the diamond that may look like a ripple. Caused by an irregularity in the diamond’s structure. These are more easily seen in SI clarity grades.

That’s all for Clarity! Just always keep in mind; Do not mistake the girdle’s reflection halfway into the pavilion as an inclusions when viewing from the side. It’s better to see it than it not being there at all. Always look at the diamond under microscope to know its true price. Although the lowest Clarity grades with the most inclusions may become fixated to you, average people who see your diamond may not notice it and instead, compliment on your stone.

The naked eye always detects a diamond’s light performance, and its color. That is why color is considered an important aspect in a diamond’s 4Cs. When we refer to a diamond’s color, what it actually means is the lack of color a diamond has.

A perfect diamond that has no hue will have a higher value. GIA grades their diamond’s color by comparing a stone under controlled lighting and precise viewing conditions to master stones of established color value.

DEF - Colorless

GHIJ - Near Colorless

KLM - Faint Yellow

NOPQR - Very Light Yellow

STUVWXYZ - Light Yellow

The yellow tint in a diamond gets more obvious as you move down the color scale. Hence, the less color the diamond has, the higher it’s color grade.

*GIA disregarded using A-C alphabets because some dealers use those grades for “in house grading” systems. The color grade D is the most expensive and rare diamond within GIA’s scale.  However, the near colorless, G-J, has proven to be just as good, as the color is still unnoticeable, and the clarity and size are within your price range.

AGS has a numerical color grade scale,where 0 grade is Colorless, to 10 being Light and Fancy Yellow shortly following after.

0.0 - 1.0 : Colorless

1.5 - 3.0 : Near Colorless

3.5 - 4.5 : Faint

5.0 - 7.0 : Very Light

7.5 - 10.0 : Light

Fancy Yellow

To get a better sense of the visual difference in color grades, check out this video where we compared D - G color graded diamonds under various lightings.

A topic that deals a lot with affecting the color is the diamond’s Cut.

A diamond’s Cut is the proportions and measurements of a diamond. The way a diamond is cut can diminish a diamond’s color because if the facets are not aligned properly, the diamond can lose its fire, scintillation, and brilliance. Fire is the colors that exit and disperse to the human eye from the light return of the diamond. Although the Fire is completely different from a diamond’s Color, it is responsible for the sparkle of the diamond. Hence it makes the appearance of the diamond more appealing.  A well-proportioned diamond will have each facet placed and angled correctly so that the light reflected back to the naked eye is maximized. For instance, a well cut diamond can reflect light in a way that would make its tint invisible to the naked eye, whereas a poorly cut diamond would make its tint more prominent. In other words, the better the cut, the less prominent the color is when viewed from face up.

There are two main factors that can hurt or improve a diamond in different aspects when it comes to a diamond’s color grade. The fluorescence and tint.

Fluorescence is the trace minerals in a diamond, that causes it to glow under UV (Ultra Violet) light or certain lighting conditions. Fluorescence comes from the source in where the diamond was mined. If the stone was found in an area where there was a lot of heat and left-over boron around the diamond, there will be Fluorescence within that diamond.

None

Faint

Medium

Strong

Very Strong

The most common color of fluorescence is blue. However, there are other colors such as orange, white, green, blue and yellow.  Blue fluorescence involves nitrogen atoms aligned in array within the carbon lattice. In most cases, Strong and Very Strong blue fluorescence makes the diamond appear hazy/milky. Medium blue fluorescence seldom makes the diamond hazy, while faint blue fluorescence almost never makes the diamond appear hazy.

Fluorescence can be bad if it affects the appearance of the diamond, causing it to look oily or milky.
This is caused mostly in daylight where the UV light rays from the sun activate the boron particles in the diamond, changing its appearance. The boron material is brought out by these factors and if the light is very strong, it can diminish the look of the diamond. Most of the time, very strong fluorescence can mask the true color of a diamond.

For example, when you are viewing diamonds under a well-lit ultraviolet light, a lovely blue-ish white diamond captures your eye. You can’t help but to buy it, so you return home with your new possession only to notice that this beautiful blue-ish white diamond you saw in the store has now turned yellowish-white! This can happen because blue is a complementary color of yellow, and in turn, whitens the look of a yellow-white diamond under daylight, or ultraviolet lights.

It may be good for a diamond to possess fluorescence if it enhances the diamond’s appearance.
Fluorescence can lower the cost of a diamond, which may be good for clients looking to buy diamonds with high clarity grades. Depending on the fluorescence, it can sometimes improve the color of a diamond. Faint fluorescence can make a positive effect on color grades G and below, while Very Strong fluorescence would normally overdo it.

Basically, Fluorescence rarely affects a diamond’s sparkle and brilliance, and it can make some diamonds appear brighter and whiter in warmer colored diamonds. Do note that since yellow tinted diamonds are usually undesirable, a yellow fluorescence in the diamond can make the price more affordable, whereas a blue fluorescence will increase the cost of yellow tinted diamonds.

Even though diamonds can be found in many colors, the most common diamonds usually contain tints of yellow or brown, and the slightest tint will have a big impact on the diamond’s price. The term “off color” describes when the diamond’s purity is destroyed by a tint of color. Brown tints are usually undesirable because they look dark when mounted. Diamonds with a brown secondary undertone may also detract from the color, making diamond more affordable. Although the tint and color are affected by the environment you are viewing the diamond in, it is best to view it in a room fully lit with plain walls.

In the video below, we showed 3 piles of diamonds, where all of them are G Color, but with a brown, yellow and no tint.

There are many elements affecting the color in diamonds. This includes nitrogen impurities, which in turn, result in a yellow tint. Keep in mind, that once Yellow is off the colorless diamond scale, we then call it a ‘fancy color’.  As nitrogen and hydrogen are most common, you can observe many diamonds with a yellow tint in the market due to the nitrogen in the diamond absorbing blue light. A rare but noticeable element is boron. When nitrogen and structural impurities combine together, internal graining happens, which in turn, results in a tint of brown in the diamond. Grey tinted diamonds have loads amounts of hydrogen, which is the cause for the grey color. Colorless diamonds contain little to no impurities and are chemically pure, as a result, they are very rare.

The color of the gold metal can affect a diamond’s appearance. Diamonds reflect light to the viewer’s eye as much as the material used on ring setting. Not choosing the perfect mount for diamonds can make it look larger or smaller, brighter or darker, whiter or more off color, or brilliant or dull. It is important to get the right metal for diamonds for this reason.

Some say for yellow tinted diamonds, they would look best on platinum metals, while others say it will look just as good with a yellow gold metal or an alloy, but to each their own. This is where contrast plays a big part, because if you have a Near Colorless diamond, around the grade K, and you place it in a platinum or white gold setting, the contrast will be increased, revealing an even more yellow color. Since G and H are Near Colorless and are on the upper grade on the Color scale, you should put it in white metal. For lower end of Near Colorless scale, such as I or J, where it shows a slight yellow tint, you would want to put it in yellow or rose gold.

Colorless Diamonds have more options when it comes to choosing mounts. Why? Simply because, they are colorless. This does not mean that you can choose unwisely, because different metals can still make an impact on your colorless diamond.

If you take a yellow gold metal and set your Colorless Diamond on it, the diamond will appear to contain yellow tint despite it being Colorless. If you do not want to add color to your diamond, white gold or platinum usually does the trick. Also, Platinum and White gold metals are great for durability! They last longer than others, and you will not have to get them fixed as often.

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