Basic Diamond Tutorial

What you need to know before buying a diamond

In the following pages you will learn about Diamonds, and the things you need to know if you are going to purchasing a diamond in the near future.

This short tutorial will tackle each of the "4 C's", give you a solid understanding of each, show you how they relate to the diamond's actual physical beauty, and show how each of these characteristics affect the price and availability of diamonds.

Why do people buy diamonds?

When shopping for the perfect diamond, the stress of the experience can very often overwhelm the initial motivation and purpose for purchasing the diamond. Diamonds are the ultimate representation of love from one person to another. A diamond is an enduring symbol of commitment and devotion. Here at Emma Parker & Co., we see a diamond as "Love... Embodied..."!

What are the "4 C's"?

The "4 C's" are the four most prevalent characteristics about diamonds, which, coincidently, all begin with the letter "C".

They are:

  • Cut
  • Color
  • Clarity
  • Carat Weight

The importance and effects of each of these will be discussed individually in the coming sections.

Anatomy of a Diamond

Before understanding cut, it is important to understand the different parts of a diamond. This will allow you to understand how each part of the diamond affects the visual beauty of the diamond to your naked eye.

Diamonds are divided into three main sections. These sections are called the CROWN (the top part of the diamond), the GIRDLE (The band which wraps around the diamond), and the PAVILION (the lower portion of the diamond). See Figure 1 below.

Figure 1

Graph showing facets of a diamond
LIGHT GREEN is the CROWN of the diamond.

WHITE is the GIRDLE of the diamond.

DARK GREEN is the PAVILION of the diamond.

The Crown and Pavilion are made up of external surfaces called FACETS. These facets act like mirrors, reflecting light that hits them. It is the combination of these facets that will either cause the diamond to reflect light (LIGHT RETURN) or to allow light to pass through (LIGHT LEAKAGE). Each facet and each group of facets has a specific purpose and function in affecting the appearance of the diamond. See Figures 2 and 3 below:

Figure 2

Graph showing facets of a diamond

This is the Crown of the diamond.

WHITE is the TABLE of the diamond.

BLACK is the STAR FACETS of the diamond.

LIGHT GREEN is the BEZEL FACETS of the diamond.

DARK GREEN is the UPPER GIRDLE FACETS of the diamond.

Figure 3

Graph showing facets of a diamond

This is the of the diamond.

DARK GREEN is the PAVILION MAIN FACETS of the diamond, also referred to as the LOWER HALVES.

LIGHT GREEN is the LOWER GIRDLE FACETS of the diamond.

The WHITE dot in the middle represents the CULET. If the diamond has one, that is where it will be.

Polish & Symmetry


Polish is the finish of each of the facets of the diamond. Once the cutting of a diamond is finished, the cutter will then polish the diamond using a polishing wheel with exceptionally fine abrasive diamond grit. This process is done to remove any roughness from the outside of the diamond, to make the facets totally clear, and to give the diamond luster.

Different certification companies give different top grades for Polish, some using the term Excellent, and some use the term Ideal. In truth, both are the same thing. Most slight issues with polish that would cause a stone to be downgraded from an Excellent grade to a Very Good grade, are completely invisible to the naked eye; totally imperceptible with out the aid of strong magnification such as a microscope.


Symmetry, as it is discussed here, is the EXTERNAL SYMMETRY of the diamond. It covers how symmetrical pattern of facets has been cut into the diamond, the shape of the facets, the symmetry of the pattern on the outside of the diamond, etc. Common causes for a diamond to not receive a top symmetry grade are issues like the Table being off center, misshapen facets, skewed patterns, extra facets, etc.

Once again, the slight differences in symmetry are totally imperceptible to the naked eye. The differences between a stone that receives Excellent Symmetry, and Very Good Symmetry, will only be visible under the magnification of a microscope.


The PROPORTIONS of the diamond are critical to the diamonds optical beauty. They will determine the path light takes through the stone. They will also determine the amount of light that the diamond reflects as a whole. There are many measurements that affect PROPORTIONS. We are going to go over them one at a time, from the most basic, to the most complex.

Here are proportion graphs from American Gemological Society (AGS). See Figure 5 below.

AGS Graph

Figure 5
AGS Dimension Graph

For the purpose of this discussion we will use the AGS Graph, as it is slightly easier to read.



The DIAMETER is simply the distance from one edge of the diamond to the opposing edge.


The measurement of depth is the distance between the TABLE of the diamond and the CULET of the diamond. (As seen in Figures 2 and 3 above) We see the DEPTH measurement graphed in Figure 5 as 62.8%. This percentage is the actual DEPTH measurement, as measured in millimeters, divided by the average DIAMETER of the diamond.

Depth can have several effects on the diamond. A diamond that is cut shallow will have a larger appearance, whereas a diamond that is cut deep will have a smaller appearance. This is referred to as SPREAD FACTOR. SPREAD is simply the diameter of the diamond. If two stones have the same weight, but one is significantly deeper (taller) than the other, it will hold more of its weight in the bottom of the diamond, and will have a smaller face-up appearance, i.e. less SPREAD.


The TABLE facet is the main facet on the top of the diamond as shown in Figure 2. This measurement is the WIDTH of the TABLE facet. The TABLE has been graphed in Figure 5 as having a 55.9% measurement. This percentage is the actual TABLE measurement, as measured in millimeters, divided by the average DIAMETER of the diamond.


The GIRDLE measurement is the measurement of the band going around the diamond, as seen in Figure 1. This measurement can be graphed several ways; average width measurement, smallest and largest width measurements, or with a word grade, such as, Thin, Medium, Thick.

The GIRDLE measurement affects two issues in general.

  1. Durability
    If the GIRDLE is too thin, this can affect the durability of the stone, making it more susceptible to damage or chipping during the setting process, or while being worn.
  2. Hidden Weight
    If the GIRDLE is too thick, this can be a sign of what is referred to as HIDDEN WEIGHT, or weight that does not contribute to the visual size of the diamond. The downside to this is that, since diamonds are priced according to weight, you are paying for weight that you don't see. This is, however, very slight in most cases.


The CULET is the small point at the bottom of the diamond. This is shown as the small white dot in Figure 3. Culets come in all sizes...from LARGE to VERY SMALL, and can even be graded as POINTED or NONE. In Figure 5, we can see that this CULET is graded as POINTED. This means that there is no flat surface at the bottom of the diamond, but that the CULET comes to a point. If you look at Figure 4, which is the graph from the GIA certification, you will see that they grade the CULET as NONE, which is exactly the same as POINTED.

The CULET really has only one significant visual impact on the stone. It can create a "window" effect through the stone if it is big enough.

Round Diamond with a Pointed Culet

Figure 6
3d Diamond Model with closed culet

Round Diamond with a Large Culet

Figure 7
3d diamond model with open culet

When you look at the images in Figures 6 and 7, you can see the effect that the culet has on the diamond. In Figure 7, you can clearly see a "hole" in the diamond, where as that is not visible in the diamond pictured in Figure 6. Certain shapes of diamonds do look very attractive with a large CULET, such as antique cuts, etc. This will be addressed further in the Diamond Shape sections of this tutorial.

Crown Height

CROWN HEIGHT refers to the "height" of the diamond above the GIRDLE. Figure 5 lists the CROWN HEIGHT for this diamond as 15.3%.

Pavilion Depth

PAVILION DEPTH refers to the "depth" of the diamond below the GIRDLE. Figure 5 lists the PAVILION DEPTH for this diamond as 43.4%.

Crown Angle

The CROWN ANGLE is the angle at which the BEZEL FACETS (as seen in Figure 2) are oriented in relation to the TABLE. For this diamond, we can see that the graph in Figure 5 shows a CROWN ANGLE of 34.7 degrees. This measurement, when considered in conjunction with the PAVILION ANGLE, can tell you a great deal about the diamonds LIGHT RETURN. These measurements will tell you how the diamond reflects the majority of the light that enters it.

Pavilion Angle

The PAVILION ANGLE is the angle at which the PAVILION MAIN FACETS (as seen in Figure 3) are oriented in relation to the TABLE. For this diamond, we can see that the graph in Figure 5 shows a PAVILION ANGLE of 41.0 degrees. This measurement, when considered in conjunction with the CROWN ANGLE, can tell you a great deal about the diamonds LIGHT RETURN. These measurements will tell you how the diamond reflects the majority of the light that enters it.

Minor Facets

The measurements on the graph also include certain measurements that deal with the MINOR FACETS of the stone. These are fully discussed in our Minor Facets tutorial.

AGS Ideal Cut Grade/GIA Excellent Cut Grade

In the world of diamonds today, there are two major cut grade systems for round diamonds. American Gemological Society's (AGS) Cut Grade and Gemological Institute of America's (GIA) Cut Grade. Both laboratories published their cut grade systems after extensive research and scientific testing. Both cut grades do overlap, however they approach the principle of cut grading from opposite sides of the spectrum.

VERY IMPORTANT NOTE:Conflicting vocabulary can be one of the most frustrating issues when trying to learn about diamonds. The two leading certification companies in the world, AGS and GIA, use very similar vocabulary in such a way that it confuses just about every person who is learning about diamond for the first time. See the table below to help keep the vocabulary straight and avoid confusion.

Characteristic AGS Term GIA Term
Cut, Polish, Symmetry Ideal
Very Good
Very Good
Fluorescence Negligible None
Culet Pointed None


The AGS Approach

AGS takes a very scientifically bound approach to the question of cut grade. Cut grades are assigned using a number system ranging from 0 - 10, with 0 being the best, or what is called IDEAL. AGS takes into consideration issues which are not visible to the human eye, and demands utter perfection from a diamond before bestowing upon it the highest cut grade AGS will give...Ideal Cut.

The key behind AGS's cut grade system is a small piece of technology known as ASET (Angular Spectrum Evaluation Technology) pictured below.

Figure 8 - Courtesy of AGS

This technology is very simple. In order for a diamond to sparkle, its facets must reflect light (LIGHT RETURN). In essence, facets that function properly, are functioning as MIRRORS, hence they will reflect something that is put "in front" of them, or as the case may be... over them.

The three colors of the ASET simply tell us as the angle at which the facets are reflecting the light. The GREEN will show all light that is reflecting from a 0 - 45 degree angle, the RED will show all light that is reflecting from a 46 -75 degree angle, and the BLUE will show all light that is reflecting from a 76 - 90 degree angle. WHITE is the absence of LIGHT RETURN, or what is referred to as LIGHT LEAKAGE. Where you see WHITE, light is passing through the diamond without being reflected back to your eye.

Keep in mind that the higher the angle of LIGHT RETURN, the stronger the brilliance when viewed by the naked eye. RED and BLUE is what we want to see, with as little GREEN as possible. Pictured below are several examples of diamonds, all with different PROPORTIONS that show differences under the asset. Notice the sharp increase in GREEN and WHITE as the diamonds go down in their cut grade.

Figure 9 - AGS Ideal Cut
AGS Ideal Cut Reflector Model

Figure 10 - AGS Cut Grade 4/Good
AGS Good Cut Reflector Model

Figure 11 - AGS Cut Grade 7/ Fair
AGS Fair Cut Reflector Model

Figure 12 - AGS Cut Grade 10/Poor
AG Poor Cut Reflector Model

One of the unique characteristics of the AGS cut grade system is that of Polish and Symmetry. For a diamond to be awarded AGS Ideal, this diamond must also have Ideal Polish and Ideal Symmetry. If either of these categories does not receive an Ideal grade, the diamond's cut grade will be downgraded from Ideal to Excellent - irregardless of the light performance of the diamond.

It is important to understand that the difference between Ideal Polish and Symmetry, and Excellent Polish and Symmetry is extremely slight and completely invisible to the naked eye.

The GIA Approach

For cut grading, GIA approaches the issue much different than AGS. The GIA cut grade system is one that is based on HUMAN EYE OBSERVATION. Although taking the science of reflection into consideration, GIA chooses to view cut grading through the eye of the consumer.

GIA formed the basis for its cut grade system by surveying 70,000 individuals with 20 different diamonds, and asking each person to rank the stones by beauty. The characteristics of the diamonds were carefully selected, and the responses of those surveyed were recorded and tabulated. These real world results formed the basis for the GIA Cut Grading System.

Because GIA chose to base its cut grade on HUMAN EYE OBSEVATION, the tolerance of the cut grade is, naturally, more lenient than that of AGS. It is important to remember that the diamond is being purchased to be beautiful to the naked eye of the wearer, as well as those who view it. From the moment the diamond is worn, it is going to be under constant HUMAN EYE OBSERVATION. Seeing then, that this is the state of scrutiny that the diamond will be under for most of its lifetime, the basis of the cut grade on HUMAN EYE OBSERVATION makes common sense.

Here are some examples of how GIA Excellent stones could appear under REFLECTOR TECHNOLOGY. These images represent looking at the diamond through the Ideal-Scope. The Ideal-Scope is a single-color reflector, which shows light return and light leakage.

Figure 12 - Courtesy of Ideal Scope
Ideal Scope Reflector Tool

Very simply, a diamond is placed in a clear tray over a light panel, with the ideal scope on top of it. All of the light that the diamond reflects, LIGHT RETURN, will be seen in two colors, red or black. The red is a reflection of the pink/red plastic while the black is a reflection of the shadow caused by the viewer's eye through the hole in the top of the scope. The highest angle of light return is black, so this is the strongest, followed by the darker reds and then the lighter reds/pinks.

White, under the Ideal-Scope is a result of LIGHT LEAKAGE (light that exits the bottom of the diamond), and is actually the white, lighted background that the diamond is sitting over. Because the diamond is not reflecting light back in these areas, you are able to look through the stone and see the white background behind it. Not all LIGHT LEAKAGE is visible to the naked eye however, so it is important to take what is seen under the Ideal-Scope into consideration along with all of the other information pertaining to the diamond. A decision should never be made based solely on one piece of data.

Both of the diamonds below are GIA Excellent cuts.

Figure 13
GIA Excellent Cut Reflector Signature

Figure 14
GIA Excellent Cut Reflector Signature

You will notice that there is much more white in the center of the second diamond, Figure 14, than the first one, Figure 13. This is because the second diamond has more LIGHT LEAKAGE in the center of the stone. The reason that both stones receive a GIA Excellent grade is because the GIA Cut Grade system is based on human eye observation, focusing on brightness. Both of these stones are going to be beautiful and bright, even though the first diamond has superior LIGHT RETURN.

What each person can see with the naked eye is different, and indeed there are people who will be able to see a difference between these two stones with the naked eye. There will also be individuals who will not able to see a difference between these stones. GIA's study concluded that amongst the observers polled the majority was not able to distinguish a significant difference between the two stones. Personal preference will determine where your preferences lie.

In addition, the GIA cut grade takes into consideration mostly factors that affect the diamonds beauty to the naked eye. For example, under the GIA cut grade system, diamond finish, i.e. Polish and Symmetry, are permitted to be Very Good, while still maintaining a cut grade of Excellent.


Color Grades

Color grades are categorized by a letter grade. The scale of color begins with D color, which is the whitest, to Z color, which is the darkest.

Most diamonds purchased for engagement rings, solitaire pendants, and diamond studs, are purchased from the D - K range of color, whereas many of the smaller stones in jewelry are lower color ranges.

Figure 15 - Courtesy of GIA
GIA Color Grading Chart

Color is organized as follows

D,E,F Colorless
G,H,I,J Near Colorless
K-Z Tinted

Diamond color is graded with the diamond upside down. The reason for this is that, since color is held within the body of the gem, it is important to observe the diamond from an angle at which the diamond's sparkle will not interfere with the observer's ability to look into the gem and see the color.

The key to color is that everyone sees color differently. Color sensitivity is something that is entirely unique to each person. This is where a "window shopping" trip to your local mall diamond store comes in handy. Before picking a diamond online, head down to the mall and ask to see several colors of diamonds laid out for you. This will give you a great feel for how much color you can see in a diamond.

Bring a white business card with you and ask to see several loose diamonds of varying color grades. Fold the white card in half and rest the diamonds, upside down, in the card. Really when doing this you should be under non-diffused fluorescent light, but the jewelry store lighting should be sufficient for this exercise. By placing the diamond upside down, and looking through the pavilion of the diamond, you should be able to see very slight color differences in the diamonds. Then flip the diamonds right side up, and observe them to see how much color you can see in the face up position.

Cut's Affect on Color

The cut of the diamond has a major affect on the visible color of the diamond. The color of a diamond is kept within the gem; that is why color is best seen from the bottom of the diamond. The reason that cut can positively affect a diamond's face up color, is because when observing a diamond with strong LIGHT RETURN (where the diamond is reflecting a large percentage of light), the reflected light blocks the viewer's ability to see the actual body of the gem. Since color is held in the body of the gem, and the viewer is seeing more LIGHT RETURN than the actual gem itself, the diamond's color is less visible when the diamond is in the face up position. When a diamond is said to face up white, this is what is being referred to.


Fluorescence is a phenomenon that occurs in about 50% of all diamonds mined. It occurs when the element Boron is present during the formation of the diamond. The result is that the diamond will "fluoresce" or glow under a black light. While Fluorescence comes in many different colors, blue is the most common, and the least worrisome. Many consumers feel the need to stay away from any Fluorescence, however, this is due to the lack of proper information.

Fluorescence is graded in levels of None, Faint, Medium, Strong, and Very Strong.

Figure 16
Diamond Fluorescence

In Figure 16, you can see the effect the fluorescence has on a stone under a black light. Since this glow can only be seen under black light, the wearer would have to be in a place where black lights are used, such as a nightclub, to ever see the diamond glow in a manner such as this.

Fluorescence can have two noticeable impacts on a diamond.

  1. It can help the face up color of a diamond. In a lower color diamond, such as a I  or J color, the presence of fluorescence can cause the diamond to appear whiter face up than a diamond of the same color without fluorescence.
  2. The fluorescence can cause the diamond have an oily, milky, or hazy appearance under strong, direct light, such as sunlight or spot light. However, this does not happen all the time. This really only becomes an issue with diamonds that have strong, or very strong fluorescence, and it does not happen to all of them. A simple way to avoid getting one of these is to ask the vendor representing the diamond to take the diamond into a strong lighting source, and examine it for you. The vender should give you an honest opinion about any visible fluorescence, because it is something that you will see in the sunlight, and to be dishonest about this will just about guarantee an unhappy customer and a returned diamond for the vender.
In general, fluorescence is not a reason “not” to buy a diamond. It is more important to know what affect the fluorescence has on the stone. Some of the most beautiful diamonds I have ever seen had strong fluorescence.
Clarity Grades
Clarity grading is intimidating, but really quite simple. Stones are graded in the following grades:
  • Flawless (FL)
  • Internally Flawless (IF)
  • Very, Very Slightly Included 1 (VVS1)
  • Very, Very Slightly Included 2 (VVS2)
  • Very Slightly Included 1 (VS1)
  • Very Slightly Included 2 (VS2)
  • Slightly Included 1 (SI1)
  • Slightly Included 2 (SI2)
  • Slightly Included 3 (SI3) Grade not given by GIA or AGS
  • Imperfect 1 (I1)
  • Imperfect 2 (I2)
  • Imperfect 3 (I3)
As you can see…the clarity grades are really only acronyms for the grade they represent. This will make it much easier to remember, and much easier to understand when you start talking diamonds with a vender.

Types of Inclusions
There are many types of inclusions that you will find in a diamond. Each type of inclusion can affect the diamond in a different way. Knowing the types and understanding their affect on the stone will help you to feel more comfortable when viewing a diamond’s clarity.
  • Pinpoint
    • A pinpoint is a tiny crystal that forms inside of the larger crystal that will become the diamond. Pinpoints are tiny, and are almost never visible to the naked eye.
  • Feather
    • A feather is really a small “crack” in the diamond. In most case, it is totally harmless. The diamond is not broken, or damaged, nor is it going to just break in half one day while it is being worn.
How much of an impact a feather will have on the diamond is greatly dependant on the placement of the feather within the diamond, and the size of the feather. Most feathers are not big enough, and not in a position in which they will affect the diamond’s structural integrity. The best way to make sure that a feather in a stone you are interested is safe, is to speak with your diamond vender about it. Also you can have the stone appraised by a reputable, independent appraiser who will be able to give you an additional opinion.
  • Crystal
    • A crystal is just that, a smaller crystal that formed inside the larger crystal which eventually became the diamond. Crystals can be white or black, they can be very visible or totally invisible, depending on size, color, and location. Crystals don’t pose any structural risks to the diamond and are one of the most common inclusions.
  • Needle
    • A needle is a type of crystal. When observed under magnification it resembles a small needle. Most of these are small, faint, white inclusions, and should not be any cause for worry.
  • Clouds
    • Clouds are groupings of pinpoints, and pinpoints, as we know, are tiny crystals. So, in essence, Clouds are groupings of tiny crystals. A cloud is one of the best inclusions you can have because it is very difficult to see.
Many people think that because the diamond has a cloud, it will appear cloudy. In the majority of cases, this is just not true. Even large clouds can be virtually invisible, even under a 10x loupe. Since many clouds are so faint, they are translucent, allowing light to pass directly through them. They are also almost always invisible to the naked eye, and are a wonderful way to sacrifice on clarity without negatively affecting the diamond.
  • Natural
    • A natural is a portion of the diamond that was not cut or polished. This occurs when during the cutting of the stone, the cutter leaves a small piece of the rough uncut and unpolished. To the inexperience eye, it can appear that the diamond is chipped, but a close examination under a microscope will show otherwise. Common places for this are near the girdle.
Naturals can also be indented. When this is the case, they really resemble chips, but again, close inspection under magnification will show that they are not.
  • Knot
    • A knot is a crystal that reaches to the surface of the diamond after the diamond is cut. Knots usually like a raised area on the surface of the diamond facet.
  • Cleavage
    • Diamond cleavage is a straight crack with no feathering. A cleavage has the potential to split the diamond apart along its length if it is hit at the correct angle.
  • Cavity
    • An open cavity in the diamond.
  • Chip
    • Where a piece of the original diamond has been chipped off.
  • Bearding
    • Bearding is when hair-like lines that can occur around the girdle during the cutting process. Minimal bearding is usually not a problem, but extensive fringing is often polished away or removed by recutting the diamond.
  • Internal Graining/Surface Graining
    • Graining is simply a characteristic structureal irregularity in the diamond. It is the visible structure of the diamond at the molecular level. Graining usually appears as incredibly faint lines in the diamond, only visible under magnification. They pose no threat the diamond, and in fact, virtually every diamond has a certain amount of graining.
Graining is one of the best inclusions you can have because it is virtually impossible to see with the naked eye. These inclusions are extremely faint. It can be very difficult to find these imperfections under a 10x loupe, let alone with the naked eye.
  • Twinning Wisps
Twinning wisps are basically an inconsistency in the formation of the molecules that make up the crystal. This leads to slight inconsistencies in the gem, which can be viewed under very high magnification.
Similar inconsistencies can be viewed in the ice cubes that you make in your freezer by observing that the ice sometimes not perfectly clear all the way through, but that there are lines of white or haziness in the ice. These inconsistencies in the formation of the crystal of ice are what causes these. So it is with diamonds.
Twinning wisps are invisible most of the time, and are a great inclusion to have in lower clarity diamonds because the fact that they are so faint makes them next to impossible to see with the naked eye.
Clarity Enhance Diamonds
Clarity enhanced diamonds are diamond that have been treated in some way to improve the visible clarity of the stone. The two most popular methods of enhancing the clarity of a diamond are by LASER DRILLING and FILLING the diamond.
In short, the diamond is drilled with a laser. Sometimes the laser can then be used to burn away or lighten an inclusion. If the inclusion is a cavity in the stone, the stone can be drilled and then a glass like substance is injected into the inclusion through the hole that has been made.
For more information on clarity enhanced diamonds, you can refer to the company that invented the process at their website,
Clarity to the Naked Eye
It is important when looking at clarity to remember that when the diamond is being worn, the only grading tool being used on it for clarity is the human eye. In general, most diamonds that are graded by reputable laboratories as a VS2 or better will be eye clean. There are also many eye clean SI1’s and SI2’s, and these stones make a wonderful price point to purchase at. They might be harder to find, but if you are open to sacrificing a little clarity, you can get more for your money.
For individuals who are not concerned with what they may or may not see, but with what they know about the diamond, the higher clarity grades are there for you. If a diamond with little or no flaws is what you are interested in, the grades of IF – VVS2 are where you want to stay. Sometimes knowing is more important than seeing, and this is a personal decision, driven by personal preference.
Remember that there is no right and wrong decision. Whatever you decide, you want to be happy that you made that decision.

What is it?
Carat weight is simply the measurement unit for determining the weight of a gemstone. One carat equals one fifth of a gram. Diamonds are weighed in either hundredths of a carat, i.e. 1.25ct or thousandths of a carat, i.e. 1.254ct. How detailed the weight is depends on the lab that is weighing the diamond.
How does it affect visual appearance?
Although carat weight is commonly referred to the “size” of the diamond, this is a misnomer. The actual, visual size of the diamond is much more dependant on the diameter of the diamond than on the carat weight of the stone. It is not uncommon to have two stones of the same weight that look very different in size to the naked eye. It is important to keep this in mind when shopping for a diamond.
How does it affect price?
Diamonds primary pricing is determined by three factors; weight, color, and clarity.
For the weight factor of pricing, diamonds are priced on a “per carat” basis. Therefore, if the per carat price of a 1.50ct diamond is $1000, the price for the diamond itself would be $1500.
Per carat prices change as the stones’ weights reach different levels. Typically the price of diamonds changes at .50ct, .70ct, .90ct, 1.00ct, 1.50ct, 2.00ct, 3.00ct, 4.00ct, etc.
At each of these stages, the “per carat” price can change anywhere from 10% - 50%. These weights are sometimes referred to as the “magic numbers”, as purchasing a diamond just under the “magic numbers” can save the customer a great deal of money.
Although this works in theory, in reality it is much more difficult that this. Diamonds that fall just under the “magic numbers” are scarce and difficult to find. Although it would be nice to buy a diamond that is 1.99ct to try and avoid the price change at 2.00ct, it is virtually impossible to find such a diamond, especially one that is well cut.
Knowing where the “magic numbers” are and how they work can come in handy should you stumble upon the right stone. It can also show  you when a compromise on some other aspect of the diamond might be a good idea to get into a “magic number” diamond that can save you a lot of money.
Diamond Scanners
As technology has become more advanced, computers have made their way into our everyday lives, the diamond industry has been no exception. One of the most powerful tools that technology has brought to the world of diamonds is that of the “non-contact scanner”. Non-contact scanners are devices that use cameras and light, combined with powerful software to scan and measure diamonds.
They do this by taking “pictures” or frames, between 3,000 – 20,000 frames, of the diamond’s profile while the diamond is rotating on a stage. From these images, the software constructs a virtual model of the diamond, complete with measurements and proportions.
In addition, some of these scanners and software packages allow the user to manipulate the model of the stone and place it in different lighting conditions and situations. The program actually provides a photo-realistic view of the diamond right on the user’s computer screen. The technology is so accurate that diamond buyers can actually make purchasing decisions based entirely on the models generated by these scanners, without ever seeing the actual diamond.
The best part is that, through the advent of technology, venders are able to deliver these models direct to you, just like we do here at Emma Parker. This allows you to get a very realistic view how the diamond you are purchasing has been cut.
The three most popular are the Sarin, Megascope, and Helium Scanners.
The technology of reflectors has already been touched on in the section of cut in this tutorial. Reflectors are simply that. They are devices which show the user the reflective capabilities of the diamond. There are several reflective devices out on the market today, all of which do pretty much the same thing and have just about the same level of effectiveness. The most common are the Ideal-Scope, ASET, and Firescope.
The simple premise of how reflector technologies work is detailed in the Cut section of this tutorial.
GIA Diamond Dock
The GIA Diamond Dock is a lighting source that combines direct light with diffused light to create a true daylight appearance. It has proven to be, in my experience, the most accurate re-creation of “man made” daylight available.
The GIA Diamond Dock is the basis for the GIA cut grade. The 70,000 observations that GIA conducted to formulate the basis for the cut grade, were conducted under the lighting of the GIA diamond dock.
The diamond dock is also useful for photography and color grading. The focus on the diamond dock is to emphasize the brightness of the stone. It gives an excellent view of how the stone will perform out in the real world.
GEMEX Brilliance Scope
The GEMEX Brilliance Scope is a technology that exposes the diamond to strong, direct light at 5 specific different angles…it then takes a triple exposed image of the stone. The grading software then breaks these images down to a pixel basis, and measures the amount of White Light (Brilliance), Colored Light (Fire), and Scintillation (The movement of light within the diamond) being given off by the diamond. The software then grades the results based on a database of other diamonds that have already been scanned, and ascribes a grade to the diamond.
The technology is certainly valid, and is used in the industry, however the results are not always indicative of how the diamond will perform in real life. Generally this applies to stones that score low, but still have a great deal of sparkle and brilliance. A good score on the Brilliance Scope will usually mean a very beautiful diamond.