by: jackksmith
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Date: Sat, 17 Jul 2010 Time: 10:20 AM -
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A Diamond Grading Report is a report or certificate issued by an independent Gemological Laboratory, which states that a diamond (usually over 1 carat) has been examined using various gemological instruments, compared to similar master diamonds, and has been found to contain the characteristics listed in the grading report. The Gemological Institute of America, GIA, is the largest and most well known laboratory in the world and as such, a diamond accompanied by a GIA report will cost more, although the diamond may not be worth more. GIA established the standards and methods for a diamond’s evaluation, which all labs now follow.
Article Source: DirectoryArticles.com
If you find the solitaire diamond rings are diamond that isn’t accompanied by a grading report, ask your seller to send it to a reputable lab to have it evaluated. Some points to bear in mind while buying your favorite diamond ring are discussed below:
Measurements
The measurements of a diamond are primarily used for identification purposes, since no two diamonds are exactly alike in weight, quality and measurements together. For fancy shape solitaire diamond rings like the princess, marquise or pear shapes, the overall length-to-width ratio is important because certain proportions are more appealing to the eye. To compute the length-to-width ratio of a fancy-shaped diamond ("fancy shape" means anything other than round brilliant), take the length of the diamond and divide by the width. Example: A marquise that measures 8 mm x 5 mm has a 1.6:1 ratio. Most people just write or say it as a 1.6 ratio.
Depth Percentage
Depth percentage refers to the ratio of the average depth of the diamond (from table to culet) as compared with the average diameter (which is used as the 100% figure for all diamond dimensions). The ranges that are commonly considered best for each shape vary slightly, but we will just give the basic dimensions for rounds here:
Ideal = 58 - 60%
Excellent = 60.1 - 62%
Good = 62 - 64%
Fair = 64 - 66%
Poor = over 66% or under 57%
Table Percentage
Table percentage is the ratio of the table width as compared to the total width of the diamond. For rounds, the largest diameter is used. For fancies, the smallest diameter (width as opposed to length) is used. For example, if the table measures 5.7 mm, and the total diameter of the diamond measures 10.0 mm, then the table percentage is 57%.
Finish
The finish of a diamond includes two separate factors: the polish and symmetry. The finish is a very good indicator of the care taken by the craftsman to make the diamond as beautiful as possible. This is one of the most contributing factors to the cut grade and cut quality of a diamond. We do not recommend engagement solitaire diamond rings with Poor or Fair grading for polish or finish.
Gridle
The girdle of a diamond is the middle, or widest part, of the diamond, and is measured from "extremely thin" to "extremely thick". Thin girdles are prone to chipping. Extremely thick girdles hide a lot of weight, so you end up paying for a heavier diamond that doesn't look that big. When examining the girdle, make sure that it is well-faceted and polished, since some diamond cutters will omit this step to save time and to avoid removing weight from the stone.
Polish
Diamonds are capable of taking a polish better than any other material on earth. This means that the solitaire diamond rings can be polished to have the most perfect, reflective surfaces. This is one reason why diamonds are known for their incredible brilliance. Polish may deteriorate in used or pre-owned diamond and should be something to watch out for.
Grades for polish range from Ideal (which is very rare) to Excellent, Very Good, Good, Poor, and Fair. We consider Good polish to be the minimum for solitaire diamond rings. Polish is not as important as symmetry, though, so don't get too hung up on this detail. Most other parameters will affect the visual properties of the stone a lot more than polish, as long as it is rated at least good.
Fluorescence
Some diamonds have a natural blue fluorescence under ultraviolet light. This is natural. How does fluorescence affect the beauty or value of solitaire diamond rings? The answer to that question depends on the color grade you are buying. Within the jewelry trade, fluorescence is often considered to slightly diminish the value of a diamond. This is because of supply and demand, as diamonds without any fluorescence at all are a little rarer than those with fluorescence.
Date of the Certificate
The date on the certificate is more important than you might think. If a certificate is over 2 years old, you should at least ask the jeweler to explain where it has been during that time. We admit it is possible the diamond could have been in the vault for that long, but usually diamonds sell faster than that at a jeweler that specializes in selling solitaire diamond rings. Just ask and see what they say!
Keeping these points in mind while buying diamond jewelry next time will surely help you to select the best solitaire diamond rings for your loved ones.
Jack Smith is an author who writes interesting articles on solitaire diamond rings, three stone diamond rings, and other diamond jewelry. For more information on solitaire diamond rings, you can also visit www.fireandicediamond.com.
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