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The colors of diamonds are as myriad as the rainbow. Among all, colorless diamonds (also known as white diamonds) are the most popular choice, and also form the parameter against which colored diamonds are graded. The differences between various colors are subtle and it takes a trained eye and comparison to a master set to understand the accuracy and differences. These differences that appear minute, affect the price of the diamond. This ready reckoner has been designed to help buyers understand the various factors that affect the color of diamonds and how to purchase the most valuable stone.
Just like cut, the GIA has established a set of guidelines for various grades of color also. A lettering system starting from D to Z is employed to grade various colors. Among these, D grade is awarded to highly rare and totally colorless diamonds. Grades E and F are also given to colorless diamonds while grades G, H and I are given to nearly colorless diamonds. Stones graded at K, L, M are faintly tinted in yellow while diamonds with a slightly deeper tint visible to the naked eye are graded at N, O, P, Q and R. Grades S to Z are finally given to those diamonds that are tinted deeper in yellow which progresses to a brownish shade. The tint of grades S to Z is visible to the naked eye even after the stone is mounted. Finally the grade of Z+ is given to fancy yellow diamonds. Many have wondered why the GIA grading system begins strangely from D up to Z. This is because earlier systems used not only numbers for grading colors but also alphabets A, B and C. These systems are still followed in a few places and in order to avoid confusion between other grading systems and GIA, the organization implemented this new system.
Price and color of diamonds
Among the various grades of diamond color, keeping all other parameters (cut, clarity and carat) intact, the more colorless the stone, the higher would be its value. Thus, a D to F grade stone would be quite expensive as compared to stones of S to Z grades. However, purchasers of S to Z grade diamonds need not despair that they are buying lower quality diamonds. The diamond is of high quality, and will sparkle, shine and glitter, whichever grade you buy.
Factors affecting color of diamonds
There are various factors that affect the color of a diamond:
Mounting of the stone: The metal on which a loose diamond is mounted often makes plenty of difference to its appearance. For example, if a light yellow diamond is mounted on white platinum or silver, the stone will appear whiter. On the other hand if a colorless diamond is mounted on gold it will look more yellowish. While purchasing your stone it is thus vital to consider the metal it is mounted upon, and how it will influence the original color of the stone.
Color treatments: Various color treatments are also undertaken for diamonds and colors can often be dramatically changed with these treatments. One such prevalent treatment is the HP/HT processing where high pressure and high temperatures are used to influence the color of the stone. Besides these permanent treatments, various temporary coatings can also be opted for to enhance a diamond's color.
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The clarity of a diamond determines the presence or absence of flaws in a diamond. These flaws or imperfections are either external or internal and perceptive diamond buyers must first understand what the various imperfections are. With evolving technologies, the GIA lab has established various grades for clarity these grades are from FL to I3 and are key factors for the diamond pricing. The article tries to list the main points regarding clarity that customers must consider before purchasing diamonds.
What are the imperfections affecting diamond clarity?
A perfectly clear diamond (FL) is rare and expensive from a vast number of stones just a very small percentage are flawless, a great example can be seen in our diamond price comparison engine where you can easily notice that from our huge diamond database only a dozen are flawless (FL) diamonds and their prices are 20% higher from similar VVS loose diamonds. Most diamonds have imperfections; these flaws can be present externally as blemishes or internally as inclusions within the diamond.
Inclusions can be in the form of minute spots of black, white and other colors or as colored and uncolored crystals. These are usually caused due to trace minerals in the stone from which the diamond is extracted.
Blemishes include the presence of scratches, cracks or pits on the surface of the diamond. While minute cracks may not cause any major problems, some cracks may cause the diamond to split.
Depending upon the various imperfections diamonds have, the GIA has devised various grades for determining the degree of clarity. These grades are given to diamonds based on the number of inclusions, position on the stone, composition and size. Using a magnification of 10X, diamonds are ranked with the following grades:
•· Flawless (FL) Diamonds
•· Internally Flawless (IF) Diamonds
•· Very Very Slightly Included (VVS1) Diamonds
•· VVS2 Diamonds
•· Very Slightly Included (VS1) Diamonds
•· VS2 Diamonds
•· Slightly Included (SI1) Diamonds
•· SI2 Diamonds
•· SI3 Diamonds
•· Included (I1) Diamonds
•· I2 Diamonds
•· I3 Diamonds
As the abbreviations explain the grading, FL comprises of flawless diamonds while IF comprises of diamonds that are flawless inside but have slight blemishes outside. VVS1 and VVS2 diamonds have minute inclusions that are difficult to detect even by experienced graders. VS1 and VS2 diamonds have minute inclusions too while SI1 and SI2 have noticeable inclusions. Finally the I1, I2 and I3 diamonds are those which have imperfections that can affect the brilliance and transparency of diamonds.
Modes for enhancing clarity
Today various technologies have evolved for enhancing the clarity of diamonds. One example is laser drilling where lasers are used to drill out the internal spots and acid is used to wash them out. Cracks on diamonds can also be filled easily, but the treatments are considered temporary in nature. Ask for certification and if the details state that a diamond is ‘enhanced' then be sure to compare the price. Enhanced diamonds are treated diamonds and as a customer you have the right to ask which treatments have gone into enhancing the stone, for further info refer to our Diamond Enhancements article.
What diamonds buyers must look for!
A perfectly clear loose diamond is not only beautiful but highly expensive when buying. Moreover, in an era where synthetic diamonds are in fashion, imperfections only go on to tell that the diamond is original. While perfect clarity is not the main criteria to look for while buying diamonds, buyers must keep the following issues about diamond clarity in mind while purchasing.
Type of flaw: A large visible crack may cause the diamond to break and must be avoided. Similarly a large blemish may also cause the stone to look dull and lifeless. Consider the kind of flaw your diamond has before purchasing one. Ask for certified diamonds such as GIA certified diamonds or EGL certified diamonds.
Location of flaw: Consider where the flaw is located and how it affects the appearance of a diamond. Flaws are visible only when diamonds are put in a particular position and one must avoid that while setting the diamond in jewelry.
Size of the flaw: Look for a diamond that appears clean to normal viewing. If the flaw is of a bigger size, it would be visible to the naked eye. Trends indicate that most diamond buyers opt for stones with VS1 and VS2 grading over perfectly flawless stones.
Number of flaws: Finally if a stone has a large number of flaws, it would reduce the brilliance. Thus look for a diamond with fewer flaws so the brilliance of the diamond can be appreciated.
So before you buy a diamond go and take a look at the certificate, the drawing of the diamond will show you exactly how serious are the imperfections even if you are not a diamonds pro, you can also send us a copy of the certificate and we will do our best to explain to you about your chosen stone.
Diamonds dug out of mines surprisingly, only 20% have clarity suitable for usage in jewelry. The rest 80% diamonds are put to industrial usage. Among the 20%, many have visible inclusions and very few are flawless. How ever negative the term inclusions or flaws may sound, they do have benefits. The price difference between a flawless stone and a VS stone is enormous and thus by buying a beautiful diamond that has slight inclusions that the naked eye cannot notice you save big.
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Round Diamond Cut
Round brilliant cuts are the most popular, preferred and brilliant among all the ways in which a diamond is cut. Over a century of research has revealed that this cut has the potential for the highest degree of light return. With an interesting history and vibrant types of cuts, it is no surprise that 80% sales among specifications all diamonds being reported to be those of round brilliant cut diamonds. They also enjoy an indisputably high popularity and various renowned laboratories set different cut grades for these diamonds. Finally, with the stringent dimensions that are followed, this cut ensures that many attempts have gone into cutting a diamond with the best proportions to achieve the highest degree of brilliance.
A round brilliant cut diamond is one that has 57 facets, or 58 facets including a culet . This cut is also known as the American ideal cut , old European cut, American standard cut, modern brilliant cut and brilliant cut. With varying standards of reference, this cut is called ideal as it works towards the overall purpose of giving a diamond with maximum fire and scintillation. While the round brilliant cut take longer cutting time than other cuts and lead to more loss of carat weight than standard cuts (an 8mm diameter ideal cut diamond weighs approximately 1.91 carats), these stones are renowned for their ideal crown, pavilion and girdle symmetries. It is also known that round brilliant diamonds are usually cut from octahedron crystals and from small crystals, with the loose stone resembling the shape of a cone.
History of round brilliant cut
This cut is said to have emerged from the old miner cut or the triple cut which was popular in the seventeenth century. While these ancient cuts had all facets similar to the current day round brilliant cut, the facet alignments were noted to be different. This cut gave direct rise to the Old European cut on which many experiments were done to define the perfectness of the current round brilliant. Soon Marcel Tolkowsky, a renowned Belgian diamond cutter, took up empirical calculations as a part of his PhD thesis in mathematics and gave the diamond industry the renowned Tolkowsky cut in 1919.
Types of round brilliant cut
While the number of facets for round brilliant diamonds is fixed, the proportions are not. This is what gives range to a wide variety even in round brilliant diamonds. Currently there are six different ideal cuts devised over the years. These include:
American ideal cut: This is also known as the modern round brilliant cut or the Tolkowsky cut. This cut is the benchmark of ideal cuts in North America. As per Tolkowsky who, the ideal cut must have a depth percentage of 59%, table percentage of 53%, crown height of 16%, pavilion angle of 40.75 degrees, crown angle of 34.5 degrees and pavilion depth at 43.1%. While the Tolkowsky ideal does not specify a girdle, in reality a round brilliant must have a medium and even girdle thickness to prevent chipping while the diamond is set. Besides this perfect symmetry, a minute or absent culet and perfectly aligned facets are pertinent.
Eppler cut: One variation of the modern round brilliant cut is the Eppler (European Practical Fine cut) which is the standard in Germany and other European countries. It was discovered in 1939 and is slightly different from the American ideal cut and is noted to increase the table size by 3%. This cut has a table size of 56%, crown height of 14.4%, overall height of 57.7%. The reduction in crown height leads to maintaining dispersion similar to the American ideal.
ScanDN: Scan DN (Scandinavian Diamond Nomenclature) cut is noted to have table width of 57.5%, overall height of 57.7% and crown height of 14.6%.
Other cuts: Ideal brilliant, Parker Brilliant and Eulitz Brilliant are the other types of ideal cuts. Among these, the Parker brilliant and Eulitz brilliant have been disused as the proportions cause low brilliance.
Dimensions of the cut
This cut has 58 facets, which includes the culet. In cases where the culet is not present, round brilliants are noted to have 57 facets. The crown or the upper portion of the diamond comprises of one table facet, 8 bezel facets, 8 star facets and 16 upper girdle facets. Besides these 33 facets, the pavilion or the bottom portion of the diamond comprises of 16 lower girdle facets, 8 pavilion main facets and one culet. The dimensions of factors like table size, crown angles and pavilion depth are taken into consideration while measuring the brilliance of a diamond. However as per GIA and many other laboratories, it is considered that other factors like total depth, girdle thickness, culet size, star facet length, lower girdle facet length, crown height and finish are taken into consideration while measuring the brilliance of the diamond. GIA has demonstrated that a slight variation in one factor can alter the brilliance of the diamond. Among the above dimensions, GIA reports that the relationship between brilliance of a diamond and the primary proportion factors of crown angle, pavilion angle and table size is rather complex. Also a well cut round brilliant needs to have good balance between fire and brilliance, with the stone reflecting light upwards and making the diamond appear white. While variations in any of the above factors affect the brilliance of the diamond in different ways, these three factors specially produce unusual results. Here are the specifications.
Table size: GIA specifies a table size of 56% as ideal while AGS notes a range from 53% to 57%. It is noted that as the table size of a diamond changes, the difference in the brilliance of a diamond is significant, also affecting the crown height and total depth of the diamond.
Depth percentage: This refers to the total depth of the diamond divided by the overall diameter. Tolkowsky specifies the standard at 59.3% and it is known that that this factor is the quickest indicator of quality of cut for a round brilliant. While a slight increase of up to 62.5% is acceptable, more increase in depth percentage reduces the brilliance of a diamond.
Crown angle: The crown diffuses light into various colors, and is an important parameter for the ideal diamond. 34 to 35.5 degrees is considered ideal for round brilliant diamonds. While a change in the crown angle does not show any great difference in the face up view, the profile view is greatly altered, again affecting the crown height and total depth of the stone.
Star facet length: Set at 50%, a change in this parameter causes great difference in face up view than in profile view. Also as the crown height and crown angle are not affected, the change in star facet length is not considered a pertinent factor for measuring brilliance.
Girdle thickness: Given a quantitative 3% by GIA, more thickness in the girdle increases the total depth of the diamond. Tolkowsky specifies a no girdle, however in reality it is required to prevent chipping in a diamond. It is thus measured at 1% to 2% of total diameter. Further increase in girdle thickness adds weighted look to a diamond, when it is viewed with the face up.
Pavilion angle: The pavilion functions by reflecting back the light through the top of a diamond, and thus slight change in the pavilion angle brings difference in the profile view. However the pavilion up view is not affected by minute changes. Pavilion depth and total depth are affected by changes in the pavilion angle.
Culet size: A pointed culet or the absence of a culet is considered the best for ideal diamonds. A wider culet is seen to bring about a marked difference in how the pavilion appears. Both total depth and pavilion depth are affected by changes in this parameter.
Besides the above factors, the overall diameter of a diamond is also a quick indicator of its brilliance. A round brilliant diamond must have a diameter (in millimeters) equal to 6.5 times the cube root of its carat weight. For example, a diamond of 1 carat must have a diameter of 6.5mm.
Cut grade for round brilliant diamonds
Different laboratories grade diamonds differently. The differences of grading used by a few of the laboratories are specified as under, both in quantitative and qualitative form.
GIA: The GIA diamond lab ideals have fixed reference values. It bases its cut grade for round brilliant diamonds on its experience of fifteen years, sophisticated computer modeling technologies like ray tracing and thousands of observations. Its cut grades fall in the categories of excellent, very good, good, fair and poor. Approximately 99% of diamonds graded at GIA come in the top three categories. Elements of physical design such as weight, durability and craftsmanship are also taken into consideration. GIA also uses its trademarked GIA Facetware products like cut estimators to ensure that results are predictable. GIA round cut diamonds are also featured in our search resutls.
AGS: Unlike GIA, AGS provides a range within which values are acceptable. Grades here are based on its five years of research on the light performance in diamonds. The distance of the diamond from the eye is noted to be at 25cms. The laboratory uses their AGS Performance Grading Software, the first of its kind to be used for round brilliant diamonds. It grades all 58 facets of round brilliants and measures them in three dimensions (most other labs grades diamonds on two-dimensional basis). The three factors of polish, symmetry and proportions are taken into consideration while grading. Triple ideal grading is awarded when all three parameters are in harmony. Instead of stringently quantifying different facet angles and facet ratios, the laboratory provides grading depending on where different facets intersect. AGS round cut diamonds are also featured in our search results.
Other diamond laboratories: These include labs like AGA and HCA. Amongst these, the standards of AGA are considered overtly strict. HCA on the other hand, is said to have altered its standards in 2004, to distinguish between brilliant and Tolkowsky. The specifications are measured based on a distance of 40cms from the eyes. Different laboratories also use different kinds of sophisticated equipment to measure the cut quality. These include H&A viewers, BrilliantScope, Idealscope, FireTrace and SarinDimension.
While the ideal cut is very desirable, the definition of such a cut is quite subjective and often a matter of controversy amongst many diamond experts. With various theories existing on the ideal cut and its proper parameters, quality and technique of cut are vital factors. These not only make a diamond look bigger than it actually is, but also give it more brilliance. The basis on which customers decide the right ideal diamond is to judge how beautiful it looks. While the round brilliant cut is both desirable as it is expensive, beauty lies in many other cuts also. Judge each stone by its merits and not with technical jargon. This is what will make the purchase of a breathtaking diamond very easy.
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