July 6, 2021

Jewelry and Treasures The Buying Guide: Diamond Grading Report

Today, few fine diamonds over one carat are traded without a diamond grading report, or certificate, as they are also called, from a respected research laboratory. Reports Scottsdale diamonds issued by the GIA/Gem trade research laboratory are most in-demand in the united states and many countries around world.
A grading report does more than clarify the stone’s genuineness, it fully describes the stone and evaluate all the critical factors impacting quality, beauty, and value. Grading reports can be very a good choice for a variety of reasons. The information they contain can provide confirmation of the “facts” as represented by the seller and enable one to create a safer decision when purchasing a diamond. Another, important function of reports is to verify the identity of a specific diamond at some future time, if, for example, it has been out of one’s ownership for any reason. For insurance purposes, the information provided on the report will help ensure replacement of a lost or thieved diamond with one that is really “compatible quality. inch

Reports are not required for every diamond, and many beautiful diamonds used in jewelry are traded without them. But when considering the purchase of a very fine diamond weighting one carat or more, we strongly recommend that the diamond be with a report, even if it means having a diamond taken off its setting (no reputable lab will issue a written report on a mounted diamond), and then reset to zero. If you are considering a diamond that lacks a written report, it is straightforward for your jeweler to obtain one. Or, now that GIA is giving diamond grading reports to the public, you may submit a diamond at GIA yourself.

Do not rely on the report alone

The availability and widespread use of diamond grading reports can, when properly understood, enable even those without professional skills to make valid comparisons between several rocks, and thus make more informed buying decisions. Reports can be an important tool to help you understand differences impacting price. But we must caution you not to let them restrict what you like or really want. Remember, some diamonds are very beautiful even though they don’t adhere to establish standards. In the final analysis, use your own eyes and have yourself how you like the stone.

A buyer who was trying to decide between several diamonds. Her husband wanted to buy her the stone with the best report, but she preferred another stone which, according to what was on the reports, was not of the same quality. They decide contrary to the best diamond and bought this made her most memorable. The biggest thing is that they knew exactly what these were buying, and paid an appropriate price for that specific combination of quality factors. In other words, they made an informed choice. The reports gave them assurance for the facts, and greater confidence that they knew what these were really comparing.

Improper use of reports can lead to costly mistakes

As important s diamond grading reports can be, they can also be abused and lead to invalid a conclusion and costly mistakes. The key to being able to rely on a diamond report, and having confidence in your decision, lies in finding out how to see it properly. For example, when trying to decide between two diamonds accompanied by diamond grading reports, buyers all too often make a decision by comparing just two factors assessed on the reports, color and clarity, and think they have made a sound decision. This is rarely the case. No one can make a sound decision based on color and clarity alone. In fact, when significant price differences exists between two rocks of the same color and clarity as the more expensive stone, and often it is not the better value. Having the same color and clarity is only the main total picture. Differences in price indicates differences in quality, differences you may not see or understand. With round diamonds, the information you need is on the report, but you need to realise what all the information means which causes the area make valid comparisons.

A word of caution: Do not make a purchase counting solely on any report without making sure the report matches the diamond, and that the diamond is still in the same condition described. Always seek a professional gemologist, gemologist-appraiser, or gem-testing research laboratory to confirm that the stone with report is, in fact, the stone described there, and that the stone is still in the same condition indicated on the report. There are instances where a report has been accidentally sent with the wrong stone. And, in some cases, strategic fraud is involved.

How to read a diamond grading report

Check the date issued. It is very important to check the date on the report. It’s always possible that the diamond has been damaged since the report was issued. This sometimes occurs with diamonds sold at auction. Since diamonds can become cracked or damaged with wear, one must always check them. For example, you might see a diamond with a report describing it as D — Exquisite. If this stone were badly cracked after the report was issued, however, the clarity grade could easily drop to VVS, and in some cases, dramatically reduced. Needless to say, when this occurs value would be dramatically reduced.

Who issued the report? Check the name of the research laboratory giving the report. Is the report from a research laboratory that is known and respected? If not, the information on the report may not be reliable. Several well-respected laboratories issue reports on diamonds. The best known in the united states add the Gemological Institute of America Diamond Trade Research laboratory (GIA/GTL or GIA), and the American Gemological Laboratories (AGL). Respected Western european labs giving reports add the Belgian Diamond High Local authority or council (HRD). Regardless of which report you are reading, all will provide similar information, including:

Identity of the stone. This certifies that the stone is a diamond. Some diamond reports don’t make a specific statement about identity because they are called diamond reports and are only issued for genuine diamonds. If the report is not called a “diamond grading report” then there needs to be a statement attesting that it is genuine diamond.

Weight. The actual carat weight must be given.

Dimensions. Any diamond, of any shape, should be measured and the dimensions recorded as an approach of identification, for insurance/identification purposes. The dimensions given on a diamond report are very prices and provide information that is important for several reasons. First, the dimensions can help you determine that the diamond being examined is, in fact, the same diamond described in the report, since the possibilities of having two diamonds with exactly the same carat weight and millimeter dimensions is remote. Second, if the diamond has been damaged and re-cut since the report was issued, the millimeter dimensions may provide a hint as to that something has been altered, which might affect the carat weight as well. Any discrepancy between the dimension that you or your jeweler slide by measuring the stone, and those provided on the report, should be a red flag to check the stone very carefully.

Finally, the dimensions on the report also tell you whether the stone is round or out of round. Out of round diamonds sell for less than those that are more perfectly round.

Fine diamonds are “well-rounded”.

The diamond’s roundness will affect value, therefore it is determined very carefully from measurements of the stone’s diameter, gauged at several points around around the circumference. For a round diamond, the report will often give two diameters, measured in millimeters and noted to the hundredth: for example, 6. 1951 rather than 6. 5; or 6. ’07 rather than 6. 0. These indicate the highest and lowest diameter. Diamonds are very rarely perfectly round, which is why most diamond reports will show two measurements. recognizing the rarity of truly round diamonds, some deviation is permitted, and the stone will not be considered “out of round” unless it deviates by more than the established convention, approximately 0. 10 millimeter in a one carat stone. In a one carat diamond, if the difference is 0. 10 or less, then the stone is considered “round. inch If the difference is greater, it is “out-of-round. inch

To calculate a good deviation on a particular stone, average the high and the low diameter dimension given and multiply that number by 0. 0154. For example, if the dimensions given are 8. 20x 8. 31, the diameter average is 8. 25 ( (8. 20 + 8. 31)/2). Multiply 8. 25 by 0. 0154 = 0. 127. This is the acceptable deviation permitted for this stone (between 0. 12 and 0. 13). The actual deviation in this example would be 0. 11 (8. 31 — 8. 20), well within the ceiling, which means this diamond would be considered “round. inch Some flexibility is permitted on diamonds over two carats.

Depending on degree of out-of-roundness (how much it deviates from being perfectly round), price can be affected. The greater the deviation, the bottom the price should be.

Dimensions for fancy shapes

While dimension for fancy shapes diamonds are not as important as they are for round diamonds, there are length to width ratios that are considered “normal” and deviations may result in price discounts. The following reflect acceptable ranges:

Pear shape: 1. 50: 1 to 1. 75: 1

Marquise shape: 1. 75: 1 or 2. 25: 1

Emerald green shape: 1. 50: 1 to 1. 75: 1

Oblong shape: 1. 50: 1 to 1. 75: 1

To higher understand what this implies, let’s look at a marquise diamond as an example. If its report showed the length to be 15 millimeters and the width to be 10 millimeters the length to width relation would be 15 to 10 or 1. 5: 1. This would be acceptable. If, however, the dimensions were 30 mm long by 10 mm wide, the relation would be 30 to 10 or 3: 1. This would be unacceptable; the relation is too great, and the result is a stone that looks too really miss its width. Note: A long marquise is not necessarily bad, and some people prefer a longer shape, but it is important to understand that such rocks should sell for less than people that have normal program plans. Always keep in mind the length to width relation of fancy cuts, and adjust the price for that are not in the acceptable range.

Evaluating proportioning from the report

As discussed earlier, good proportioning can be as critical to diamond as it is to the male or female who would wear it! The proportioning, especially the depth percentage and table percentage, s what determines how brilliance and fire the stone will have.

The information provided on diamond reports pertaining to proportions is critically important for round, brilliant cut diamonds. Unfortunately, it is only of minimal use with fancy fancy shape diamonds. For fancies, you must learn to rely on your eye to tell whether or not the proportioning is acceptable: are there differences in brilliance across the stone? Or flatness? Or dark spots such as “bow-ties” resulting from poor proportioning.

Evaluating the proportioning of a diamond can be as critical as evaluating the color and clarity grades. Diamonds that are cut close to “ideal” proportions, rocks with “excellent” makes can easily cost more than standard while diamonds with poor makes sell for less; very badly proportioned rocks should be priced for much less. The information on a diamond report can help you measure the proportioning and know whether or not you should be paying more, or less, for a particular diamond.

Depth percentage and Table percentage key to beauty

To determine whether or not a round stone’s proportioning, so critical to its beauty, is good, look at the section of the report that describes depth percentage and table percentage. The depth percentage represents the depth of the stone, the space from the table to the culet, as a percentage of the width of the stone. The table percentage represents the width of the table as a percentage of the width of the entire stone. These numbers indicate how well a round stone has been cut in terms of its proportioning, and must adhere to very precise standards. Your eye may be able to see differences in sparkle and brilliance, but you may not be able to discern the subtleties of proportioning. The rates on the report should fall within a fairly specific range in order for the stone to be judged acceptable, excellent, or poor.

Some reports also provide information about the the queen’s angle. The the queen’s angle lets you know the angle at which the the queen’s portion has been cut. This angle will affect the depth and table percentage. Normally, if the the queen’s angle is between 34 and 36 degrees, the table and depth will be excellent; between 32 and 34, good; between 30 and 32 degrees, fair; and less than 30 degrees, poor. If the exact the queen’s angle is given, it is probably considered acceptable. If not, there is a statement indicating that the queen’s angle is higher than 36 degrees, or is less than 30 degrees.

Depth percentage

A round diamond cut with a depth percentage between 58 and sixty four percentage is often a lovely, lively stone. You should note, however, that girdle thickness will affect depth percentage. A high depth percentage could result from a thick or very thick girdle, and once checking depth percentage on the diamond report, check the girdle information as well.
Rocks with a depth percentage over 64% or under 57% will normally be too deep or too low to exhibit maximum beauty and may sell for less. If the depth percentage is way too high, the stone will appear smaller than its weight indicates. If the depth percentage is exceptionally high, brilliance can be significantly affected. Diamonds that are so low, that is, rocks with such low depth rates, they may have no brilliance and liveliness at all. When dirty, such rocks look no better than a piece of glass.

We avoid diamonds with depth rates over 64% or under 57%. If you are attracted to such diamonds remember that they should sell for much less per carat.

Table Percentage

Round diamonds cut with tables ranging from 53% — 64% usually result in beautiful, lively rocks. Diamonds with smaller tables usually exhibit more fire than people that have larger tables, but rocks with larger tables may have more brilliance. As you see, table width affects the diamond’s personality, but deciding which personality is more desirable is a matter of personal taste.


Under finish on the diamond report, you will find an evaluation of the diamond’s gloss and proportion. Gloss serves as an indicator of the care taken by the cutter machine. The standard of the stone’s gloss is a factor that cannot be ignored in evaluating the overall quality of a diamond, as well as its cost and value. Gloss can be described on the report as excellent, very good, good, fair, or poor. The price per carat should be less on diamonds with “fair” or “poor” gloss. Cost per carat is usually more for diamonds that have “very good” or “excellent” Gloss.
Proportion describes several factors:

How the part edges line-up with one another;
whether or not the features from side of the diamond match related features on the opposite side;
whether or not features in the top area of the diamond are properly arranged with related ones in the bottom portion.

When the proportion is termed “fair”, or worse, something is out of line.
When evaluating proportion, the most important area to check is the positioning of the the queen’s (top) to the pavilion (bottom). If it is bad, it will make a visual difference in the beauty of the stone, and correspondingly in its price. To check for proper positioning here, simply look at the diamond from the side to see whether or not the features just above the girdle line-up with the features just beneath the girdle.

When the top and bottom features do not make, this implies sloppy cutting and, more important, the overall beauty of the diamond’s is reduced. This will reduce the price more than other proportion faults.

How does the girdle affect value?

The girdle is another important item described on diamond grading reports. The report will indicate whether or not the girdle is finished, or faceted, and how thick it is. Girdle thickness for instance very important for just two reasons:

It affects value, and
It affects the diamond durability.
Girdle thickness ranges from extremely thin to extremely thick. Diamonds with girdles that are excessively thin or thick normally sell for less than other diamonds. An extremely thin girdle improves the risk of chipping. remember that despite their legendary solidity, diamonds are brittle, so very thin edge positions a greater risk.

If a diamond has an extremely thick girdle, its cost should also be reduced somewhat because the stone will appear smaller than another diamond of the same weight with a more normal girdle thickness. This is because additional weight is being consumed by the thickness of the girdle itself.
There are some cases when a very thick girdle is acceptable. Shapes that have more than one points, such as the pear shape, heart, or marquise, can have thick to very thick girdles in part of the points and still be in the acceptable range. Here the additional thickness in the girdle helps protect the points themselves from chipping.

Generally, a diamond with an extremely thin girdle should sell for less than one with an extremely thick girdle because of the diamond’s increased vulnerability to chipping. However, if the girdle is much too thick (as in older diamonds), the price can also be considerably less because the stone cam look significantly smaller than other diamonds of comparable weight.

The Culet

The culet looks like a place towards the bottom of the diamond, but it is often another part, a smallish, flat gloss surface. This part should be small or really small. A small or really small culet won’t be noticeable from the top. Some diamonds, today, are sharp. This means that there in fact is no culet, that the stone has been cut lower to a point instead. The bigger the culet, the more visible it will be form the top. The more visible, the bottom the cost of the diamond. Diamond termed having large or “open” culet as with old Western european or old-mine cut diamonds are less desirable, because the appearance of the culet causes a reduction in sparkle or brilliance at the very center of the stone. These rocks normally need to be re-cut, and their price should take the requirement for re-cutting. for the same reasons, a cracked or broken culet will seriously take away from the stone’s beauty and significantly reduce the cost.

Color and Clarity

The color and clarity grades on a diamond report are the items most people are familiar with. They are critical indicators in terms of determining the value of a diamond, but as the former discussion has shown, they don’t tell the whole story about the diamond.

A word about fluorescence

Fluorescence, if present, will also be indicated on a diamond grading report. It will be ranked weak, moderate, strong, or very good. Some reports indicate the color of the fluorescence as blue, yellow, white, and so on. If fluorescence is moderate to very good and the color is not indicated, you should ask the jeweler to tell you what color the stone fluoresces. A stone with strong yellow fluorescence should sell for less since it will be more yellow than it really is when worn in sunshine or fluorescent lighting. The presence of blue fluorescence will not take away, and in some cases may manifest as a bonus since it could make the stone appear more white than it really is in sunshine or fluorescent lighting. However, if the report show a very strong blue fluorescence, there may be an slimy or milky appearance to the diamond. If the stone appears milky or slimy to you as you view it, especially in sunshine or fluorescent light, it should sell for less.

Pay attention to the full clarity picture provided

The placement, number, type, and color of internal and external flaws will be indicated on a diamond grading report, occasionally includes a plotting, d diagram showing every piece of information. Be sure you carefully note every piece of information in addition to the cumulative grade. Remember, the keeping skin problems can impact value.

The best diamond grading report cannot be issued on a fracture-filled diamond, so GIA and most other labs will not issue a written report on diamonds which have been clarity enhanced by this method. The diamond will be returned with a notation that it is filled and cannot be ranked. Reports are issued on diamonds which have been clarity enhanced by laser. Remember, however, that no matter what the clarity grade, a lasered diamond should not cost less than another with the same grade.

One last word about diamond reports

Diamond grading reports provide a very useful tool to help in comparing diamonds and evaluating quality and value. But the key to their usefulness is proper understanding of how to read them, and how to look at the stone. Those who take the time to learn and know very well what they are reading and, therefore, what they are really buying, will have a major advantage over those who do not.

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