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Mieke Vranken Jeweldesign & Goldsmitthing
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The 4 C's of Diamonds :
Intro
When you read about diamonds, the term 'four Cs' is often in the text. What exactly is the meaning of this term and where does it stand for ? In a series of Newsflashes during the next weeks you'll be given the explanation of it. It will al be Clear !The "four Cs" of diamonds stand for : *Cut *Clarity *Colour *Carat weight It are these criteria that jewellers use when they give gradings to diamonds. They are also the criteria that you have to understand when looking for a diamond that will suit you. And then often a "fifth C" pops up : Certificates. Cut Cut is the most important of the four Cs to understand. It is also the most difficult one because the brilliance of a diamond depends heavily on it. Clarity Most diamonds contain some impurities. These are called inclusions and they occur during the natural formation process. The visibility, number and size of these inclusions determine the clarity of a diamond. Clear diamonds are more brilliant, and thus are more highly prized, and priced, since they are so rare. Colour The refraction of light resulting in the sparkling of a diamond is the highest with colourless diamonds. That is why these are the most desirable ones. Slightly coloured diamonds absorb light, inhibiting brilliance. They are called 'off white'. Carat Weight A carat is the unit of weight by which a diamond is measured. Together with the previous Cs, it determines the price of a diamond. Because large pure and clear, white diamonds are found less commonly than small ones, the price of a diamond rises exponentially to its size. The Fifth C: Certificates The diamond certificate is a complete evaluation of a diamond that has been performed by a qualified professional with the help of special gemological instruments. Each stone bears its own recognisable, individual characteristics, which is listed on the certificate (or grading report). Antwerp (Belgium) is a major city in processing diamonds of high quality.
The 4 C's of Diamonds :
Diamond Cut
The shining brilliance of diamonds. You may have wondered how that light can come from deep in the heart of a diamond. That is a result of the 'diamond cut'. Diamond cut is perhaps the most important 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. The angles and finish of any diamond are what determine its ability to handle (reflect) light, which leads to brilliance. So The quality of the "cut" does make a difference in how a diamond looks.And don't confuse diamond "cut" with "shape." Shape refers to the general outward appearance of the diamond, (such as round, emerald, or pear). When you read on the diamonds' certificate "cut" that's a reference to the diamond's reflective qualities, not the shape. Take a look at the chapter 'Diamond Terminology' (further) for an explanation of the terms used in the next paragraphs. In an ideal cut diamond, 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. (see the images below) This light is the brilliance that you can see, and it's this flashing, fiery effect that makes diamonds so mesmerising. In a poorly cut diamond, less light is reflected because 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. This results in less brilliance. The Grades. All experts agree that the best cut diamonds are those that follow a set of formulae calculated to maximise brilliance. These formulae can be seen in a diamond's proportions, most importantly how the depth compares to the diameter, and how the diameter of the table compares to the diameter of the diamond. However, the variance in the proportions between an Ideal Cut and a Poor Cut can be difficult to be determined by the casual observer. Because the large importance of the cut, several grading methods have been developed. They should help consumers to determine the cut of a particular diamond. In general, these grades are : Ideal / Premium / Very Good / Good / Fair & Poor Which Cut Grade to choose. It will depend upon your own preference, which grade you want to choose. But to make the best selection, you need to understand the various grades. Don't forget that they are just guidelines. Ideal Cut 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 shaped diamonds. This cut is intended to maximise 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. Premium This grade is hard to define. In the case of round diamonds, many Premium Cut diamonds have cuts that are the equal of any Ideal Cut diamond, though they often can be purchased at lower prices. They are intended to provide maximum brilliance and fire. Very Good With these diamonds, the cutters have chosen to stray slightly from the ideal diamond proportions in order to create a larger diamond. These diamonds reflect most of the light that enters them, creating a good deal of brilliance. The result is that these diamonds fall slightly outside of some customers' preferences in terms of table size or girdle width. Generally, the price of these diamonds in slightly below that of Premium cuts because in many cases, many of the parameters of diamonds in this range, will overlap with certain parameters of diamonds in the Ideal or Premium ranges. Good Diamonds in this range offer an excellent cost-savings to customers who want to stay in a budget without sacrificing quality or beauty. The grade describes 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 Premium quality diamond. Fair & Poor These diamonds typically have been cut to maximise the carat weight over most other considerations. A diamond graded as fair or poor reflects only a small proportion of the light that enters it. So 'Big' is not always 'Beautiful' when talking about diamonds Diamond Terminology Explanation of the various "parts" of a diamond. Diameter The width of the diamond as measured through the girdle. Table This is the large, flat top facet of a diamond. Crown The upper portion of a cut gemstone, above the girdle. Girdle The narrow rim of a diamond that separates the crown from the pavilion. It is the largest diameter to any part of the stone. Pavilion The lower portion of the diamond, below the girdle. It is sometimes referred to as the base. Culet The tiny facet on the pointed bottom of the pavilion, which is the portion of a cut gem below the girdle. Depth The height of a gemstone, from the culet to the table.
The 4 C's of Diamonds :
Diamond Clarity
Considering the incredible amount of pressure it takes to create a diamond, it's no surprise that many diamonds have inclusions -- scratches, blemishes, air bubbles or non-diamond mineral material -- on their surface or inside.Diamond's clarity is referring to the presence of identifying characteristics on and within the stone, most of which are inherent qualities of the rough diamond and have been present since the earliest stages of the crystal's growth below ground. A few are actually the result of the harsh stress that a diamond undergoes during the cutting process itself. Diamonds with no or few inclusions and blemishes are more highly valued than those with less clarity. They are more pleasing to the eye and they are rarer. How are diamonds graded for clarity? Diamonds are graded for clarity under 10x loupe magnification. Grades range from Internally Flawless, diamonds which are completely free of blemishes and inclusions even under 10x magnification, to Imperfect 3, diamonds which possess large, heavy blemishes and inclusions that are visible to the naked eye. For clarity grades F through SI, inclusions (flaws) are NOT visible to the naked eye. With grades F through SI, a diamond's clarity grade has an impact on the diamond's value, not on the unmagnified diamond's appearance. The names of these grades are internationally widely spread. F-IF Flawless or Internally Flawless (two grades). No internal inclusions. Very rare. VVS1-VVS2 Very Very Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification. VS1-VS2 Very Slightly Included (two grades). Minute inclusions invisible to the naked eye and seen only with difficulty under 10x magnification. SI1-SI2 Slightly Included (two grades). Minute inclusions very difficult to detect under 10x magnification. I1-I2-I3 Included (three grades). Inclusions visible under 10x magnification as well as to the human eye. Illustration : The presence of these clarity characteristics lower the clarity grade of a diamond. They can also be viewed as proof of a diamond's identity. Most Diamond Certificates include a "plot" of a diamond's inclusions -- it is like 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. Which Clarity Grade to choose? While Flawless diamonds are the rarest but a diamond does not have to be flawless to be stunning. Diamonds with VVS and VS grades are excellent choices for both value and appearance. More affordable (and still a great choice) are so called "eye-clean" - diamonds with no inclusions visible to the naked eye. These diamonds are SI1 and SI2 and unless the recipient carries a 10X loupe (a strong jewellery magnifying glass), the inclusions won't be seen. In fact, until you drop to the "I" grade, a diamond's clarity grade has an impact on the diamond's value, not on the unmagnified diamond's appearance. As to I1-I3? Maybe when there's a diamond grade that's defined as "you can see the flaws just by looking at the diamond," nothing more needs to be said.
The 4 C's of Diamonds :
Diamond Colour
A diamond's colour is 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.Because a colourless diamond allows more light to pass through it than a coloured diamond, colourless diamonds emit more sparkle and fire. The formation process of a diamond ensures that only a few, rare diamonds are truly colourless. Thus the whiter a diamond's colour, the greater its value. To grade 'whiteness' a professional colour scale is used. It begins with the highest rating of D for colourless, and moves up 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. Diamonds graded G through I show virtually no colour that is visible to the untrained eye. Diamond Color Gradings [NOTE: Fancy colour diamonds do not follow this rule. These are very rare and very expensive diamonds. They can be any colour from blue to green to bright yellow and are actually more valuable for their colour.] Which Colour Grade to choose? Diamonds graded D through F are a treat for the eyes of anyone. They are naturally the most valuable and desirable because of their rarity. But you can still obtain very attractive diamonds that are graded slightly less than colourless. Diamonds graded G through I show virtually no colour that is visible to the untrained eye. Depending on your setting (white gold or platinum), you may wish to opt for a higher colour grade than if the setting is yellow gold. And while a very faint hint of yellow will be apparent in diamonds graded J through M, this colour can often be minimised by selecting the right jewellery in which to mount your diamond. There are many people who actually prefer the warmer glow of lower-colour diamonds to buying the most colourless diamond they can afford. Diamond Color Table
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 gemologists prefer diamonds without this effect, some people enjoy it. It's really just a matter of aesthetics.
The 4 C's of Diamonds :
Diamond Carat Weight
A carat is a unit of measurement, it's the unit used to weigh a diamond. One carat is equal to 200 milligrams, or 0.2 grams. The word "carat" is taken from the carob seeds that people once used in ancient times to balance scales. So uniform in shape and weight are these little seeds that even today's sophisticated instruments cannot detect more than three one-thousandths of a difference between them. Don't confuse "carat weight" with "karat," the method of determining the purity of gold. Keep in mind that differences in size are clearly visible... even to the untrained eye. The process that forms a diamond happens only in very rare circumstances, and typically the natural materials required are found only in small amounts. That means that larger diamonds are uncovered less often than smaller ones. Thus, large diamonds are rare and have a greater value per carat. For that reason, the price of a diamond rises exponentially to its size.
The 4 C's of Diamonds :
Diamond Certificates
A certificate is a "blueprint" of a diamond, it tells you the diamond's exact measurements and weight, as well as the details of its cut and quality. It precisely points out all the individual characteristics of the stone. Certificates also serve as proof of the diamond's identity and value. A certificate is not the same thing as an appraisal. A certificate describes the quality of a diamond, but it does not place a monetary value on the gem. An appraisal places a monetary value on your diamond, but does not certify the quality of the diamond. GIA Sample Certificate Who Issues Certificates? There are many diamond labs that issue certificates, and the Gemological Institute of America (GIA) and the American Gem Society (AGS) are two of many widely regarded and recognised diamond grading labs in the world. Not all diamond certificates are created equal but always ask for credentials of the certifying lab. And while there are many other diamond grading labs in operation (many of which produce their own grading reports), different labs have different grading standards, and some labs will be more lenient with their standards than others. Examples of recognised diamond grading labs :
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