This is the weight of a diamond measured in carats. One carat is divided into 100 “points,” so that a diamond of 75 points weighs 0.75 carats. The carat-weight of a diamond is the easiest measurement to determine. There is 0.2 grams in 1 carat, which makes 1 gram 5 carats. The word “carat” comes from the seed of the carob tree pod which is found in tropical climates. These seeds were used until this century to weigh precious gems.

How Carat Weight Affects Value

Larger diamonds are more rare and in more demand than smaller diamonds of the same quality. A one carat diamond solitaire ring is nearly always more expensive than a diamond ring made up of multiple diamonds that are similar, but smaller, even though they total one carat or more.
Diamonds that weigh just under the next full carat are typically less expensive than diamonds passing the full-carat.
TIP: As the carat weight of a diamond increases so does its rarity and therefore its price. Most importantly, two diamonds can be of equal carat-weight, but their value can differ greatly due to their cut, colour, and clarity.

A diamond certificate is completed by a third-party. A 3rd party certification is recommended as it would be easy for an unscrupulous jeweller to take advantage of an uninformed buyer and sell him/her a stone, which ostensibly has much better characteristics than it really does. There are a number of ways unsuspecting buyers might land a bad deal. If the diamond is not certified, there is a good chance you may be buying a stone that is one or more grades below stated values in terms of carat weight, colour, clarity, or cut. Without a certificate, issued by a reputable agency, such as GIA, IGI or HRD, a buyer relies on a jeweller’s integrity that the diamond’s 4C parameters are accurate and not overstated.

When we speak of a diamond’s clarity, we are referring to the presence of identifying characteristics on (blemishes) and within (inclusions) the stone. If you think about the incredible amount of pressure it takes to create a diamond and the fact that natural diamonds are not grown in a sterile laboratory, it’s no surprise that most diamonds have flaws.

Basically there are two types of clarity characteristics: inclusions and blemishes. Inclusions refer to internal flaws and blemishes refer to surface defects. However, in the diamond grades listed below, you’ll note that none of the grades include the term “blemish” – for the purposes of grading diamonds, all flaws are called “inclusions.”

Inclusions include flaws such as feathers, knots and other minerals found in the diamond. Blemishes include scratches, pits, and chips. Some blemishes may also occur during the cutting processes (most often at the girdle).

Diamonds grades range from Flawless (diamonds which are completely free of blemishes and inclusions), to Included 3 (diamonds which possess large, heavy blemishes and inclusions that are visible to the naked eye). Diamonds are graded for internal characteristics under 10 x loupe magnification and judged on the basis of five clarity factors: size, number, position, nature, colour and relief.

• F
  Flawless: No internal or external flaws. Extremely rare.
• IF
  Internally flawless: no internal flaws, but some surface flaws. Very rare.
• VVS1-VVS2
  Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10 x magnifications by a trained gemmologist.
• VS1-VS2
  Very Slightly Included (two grades). Minute inclusions seen only with difficulty under 10x magnification by a trained gemmologist
• SI1-SI2
  Slightly Included (two grades). Minute inclusions more easily detected under 10x magnification by a trained gemmologist
• I1-I2-I3
  Included (three grades). Inclusions visible under 10x magnification AS WELL AS to the human eye.

Diamonds with higher clarity grades are more valued, with the exceedingly rare Flawless graded diamond fetching the highest price. While the presence of these clarity characteristics (inclusions and blemishes) does lower the clarity grade of a diamond, they can also be viewed as proof of a diamond’s identity.  Minor inclusions or blemishes are useful because they help to identify certain diamonds. In addition, as synthetic diamond technology improves and distinguishing between natural and synthetic diamonds becomes more difficult, inclusions or blemishes can be used as proof of natural origin. GIA certificates include what is known as “plot” (map) of a diamond’s inclusions — think of it as a “diamond fingerprint.” Since no two diamonds are exactly the same, comparing the uniqueness of your diamond’s clarity characteristics with the plot provided on the diamond certificate offers assurance that the diamond you pay for is the same diamond you receive.

TIP: Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity because they are rarer.

The colour of a diamond is determined by chemical impurities and/or structural defects. Depending on the hue and intensity of a diamond’s colouration, a diamond’s colour can either detract from or enhance its value. When jewellers speak of a diamond’s colour, they are usually referring to the presence or absence of colour in white diamonds. Colour is a result of the composition of the diamond, and it never changes over time.
The formation process of a diamond ensures that only a few, rare diamonds are truly colourless. So the whiter a diamond’s colour, the greater its value.
TIP: Diamonds graded G through I show virtually no colour that is visible to the untrained eye.
[NOTE: Fancy colour diamonds do not follow this rule. These diamonds, which are very rare and very expensive, can be any colour from blue to green to bright yellow. They are actually more valuable for their colour.]
To grade ‘whiteness’ or colourlessness, most jewellers refer to GIA’s professional colour scale that begins with the highest rating of D for colourless, and travels down the alphabet to grade stones with traces of very faint or light yellowish or brownish colour. The colour scale continues all the way to Z.

Which Colour Grade Should I Choose?
Diamonds graded D through F are naturally the most valuable and desirable because of their rarity. Such diamonds are a treat for the eyes of anyone. But you can still obtain very attractive diamonds that are graded slightly less than colourless. While a very, very faint hint of yellow will be apparent in diamonds graded J through M, this colour can often be minimized by carefully selecting the right jewellery in which to mount your diamond. Keep in mind that, while most people strive to buy the most colourless diamond they can afford, there are many people who actually prefer the warmer glow of lower-colour diamonds.
TIP: Diamonds graded G through I show virtually no colour that is visible to the untrained eye. If you are setting your diamond in white gold or platinum you may wish to opt for a higher colour grade than if the setting is yellow gold.

What is Fluorescence?
Fluorescence is an effect that is seen in some gem-quality diamonds when they are exposed to long-wave ultraviolet light (such as the lighting frequently seen in dance clubs). Under most lighting conditions, this fluorescence is not detectable to the eye. While most gemmologists prefer diamonds without this effect, some people enjoy it. It’s really just a matter of aesthetics.

The diamond cut is a very important aspect of the four Cs, so it is important to understand how this quality affects the properties and values of a diamond. A good cut gives a diamond its brilliance, which is that brightness that seems to come from the very heart of a diamond. The angles and finish of any diamond is what determines its ability to handle light, which leads to brilliance.
As shown in the images below, when a diamond is well-cut, light enters through the table and travels to the pavilion where it reflects from one side to the other before reflecting back out of the diamond through the table and to the observer’s eye. This light is the brilliance we mentioned, and it’s this flashing, fiery effect that makes diamonds so mesmerizing.

In a poorly cut diamond, the light that enters through the table reaches the facets and then ‘leaks’ out from the sides or bottom of the diamond rather than reflecting back to the eye. Less light reflected back to the eye means less brilliance.
TIP: Variance in the proportions between an Ideal Cut and a Poor Cut can be very difficult to discern by the casual untrained observer.

Because cut is so important, several grading methods have been developed to help consumers determine the cut of a particular diamond.

In general, these grades are:

Ideal Cut
This cut is intended to maximize brilliance, and the typically smaller table sizes of these diamonds have the added benefit of creating a great deal of dispersion or ‘fire’ as well. Ideal quality diamonds are truly for the person who enjoys knowing that he has one of the finest things that money can buy. This category applies only to round diamonds.

Very Good
These diamonds reflect most of the light that enters them, creating a good deal of brilliance. With these diamonds, the cutters have chosen to stray slightly from the preferred diamond proportions in order to create a larger diamond. The result is that these diamonds fall slightly outside of some customers’ preferences in terms of, for example, table size or girdle width, though, in many cases many of the parameters of diamonds in this range will overlap with certain parameters of diamonds in the Ideal range.

Good
Diamonds that reflect much of the light that enters them. Their proportions fall outside of the preferred range because the cutter has chosen to create the largest possible diamond from the original rough crystal, rather than cutting extra weight off to create a smaller higher quality diamond. Diamonds in this range offer an excellent cost-savings to customers who want to stay in a budget without sacrificing quality or beauty.

Fair / Poor
A diamond graded as fair or poor reflects only a small proportion of the light that enters it. Typically these diamonds have been cut to maximize the carat weight over most other considerations.

Round Brilliant Diamonds
This shape has set the standard for all other diamond shapes, and accounts for more than 75% of diamonds sold today. Its 58-facet cut, divided among its crown (top), girdle (widest part) and pavilion (base), is calibrated through a precise formula to achieve the maximum in fire and brilliance.

Oval Diamonds
An even, perfectly symmetrical design popular among women with small hands or short fingers. Its elongated shape gives a flattering illusion of length to the hand.

Marquise Diamonds
An elongated shape with pointed ends inspired by the fetching smile of the Marquise de Pompadour and commissioned by the Sun King, France’s Louis XIV, who wanted a diamond to match it. It is gorgeous when used as a solitaire or when enhanced by smaller diamonds.

Pear Shaped Diamonds
It is shaped like a sparkling teardrop. It also belongs to that category of diamond whose design most complements a hand with small or average-length fingers. It is particularly beautiful for pendants or earrings.

Heart Shaped Diamonds
This ultimate symbol of romance is essentially a pear-shaped diamond with a cleft at the top. The skill of the cutter determines the beauty of the cut. Look for a stone with an even shape and a well-defined outline

Emerald Cut Diamond
This is a rectangular shape with cut corners. It is known as a step cut because it’s concentric broad, flat planes resemble stair steps. Since inclusions and inferior colour are more pronounced in this particular cut, take pains to select a stone of superior clarity and colour.

Princess Cut Diamond
This is a square or rectangular cut with numerous sparkling facets. It is a relatively new cut and often finds its way into solitaire engagement rings. Flattering to a hand with long fingers, it is often embellished with triangular stones at its sides. Because of its design, this cut requires more weight to be directed toward the diamond’s depth in order to maximize brilliance. Depth percentages of 70% to 78% are not uncommon.

Triangle Diamonds
This is a spectacular wedge of brittle fire. The exact design can vary depending on a particular diamond’s natural characteristics and the cutter’s personal preferences. It may be a traditional triangular shape with pointed corners or a more rounded triangular shape with 25 facets on the crown, 19 facets on the pavilion, and a polished girdle. It is definitely for the adventurous.

Radiant Cut Diamonds
This square or rectangular cut combines the elegance of the emerald shape diamond with the brilliance of the round, and its 70 facets maximize the effect of its colour refraction. Because of its design, this cut requires more weight to be directed toward the diamond’s depth in order to maximize brilliance. Depth percentages of 70% to 78% are not uncommon.

Cushion Cut Diamond
An antique style of cut that looks like a cross between an Old Mine Cut (a deep cut with large facets that was common in the late 19th and the early 20th centuries) and a modern oval cut. Recently this shape is becoming very popular.