AGS (American Gem Society ) Certifications

AGS Gemological Laboratory





The AGS Gemological Laboratory is equal to or stricter than GIA. The AGS diamond quality document, commonly called an AGS certification, provides a carefully drawn plot which illustrates the exact position, size and shape of every internal inclusion and external blemish a diamond possesses in addition to a complete full analysis of diamond proportion, color and clarity.

The AGS is the only gemological laboratory that assigns a cut grade as a numerical value between 0 and 10. The AGS system of defining cut grade is modeled after the Tolkowsky theoretical ideal brilliant which is a standard of ideal proportions and facet angles that were mathematically calculated by Marcel Tolkowsky in 1919. It also carefully considers important aspects of diamond polish and symmetry in the assignment of a cut grade. An ideal cut diamond is assigned AGS 0-cut grade. Small incremental proportion deviations from the ideal cut model assign the next higher numerical cut grade. Cut grades 1 and 2 are still considered very fine.

Fewer diamonds are available with AGS Diamond Quality Documents (AGS Certifications) compared to GIA or EGL certifications. AGS certifications are most often used by diamond cutters who wish to confirm near ideal or ideal cut diamonds. Cutters and wholesalers seldom send average or poorly cut diamonds to the AGS.

Don't confuse an AGS diamond quality report with an AGS Member Jeweler's appraisal or opinion. An American Gem Society (AGS) Member Jeweler does not have power to validate grades on behalf of AGS, or issue an official AGS report.

AGS Diamond Quality Reports provide the following information:

AGSL Number: Unique number assigned to each Diamond Quality Document

Date: Date the Diamond Quality Document was issued

Weight: Carat weight of diamond measured to one thousandths of carat

Shape and Style: Description of the diamond shape

Measurements: Length, width and depth of diamond measured in millimeters

Cut Grade: 0=Ideal, 1=Excellent, 2=Very Good, 3-4=Good, 5-7=Fair, 8-10=Poor In assigning a Cut Grade, seven factors are considered: five proportion factors, polish and symmetry.

Polish: Rating (Ideal, Excellent, Good, Fair, Poor) of polish marks left from polishing wheel used by diamond cutters to polish the facets of the diamond after cutting.

Symmetry: Rating (Ideal, Excellent, Good, Fair, Poor) of balance and alignment of the facets.

Proportions: Table %, crown angle, pavilion depth %, girdle thickness % and culet size are evaluated against specific standards and a composite rating (Ideal, Excellent, Good, Fair, Poor) assigned.

Color Grade: 0=D, 0.5=E, 1.0=F, 1.5=G, 2.0=H, I=2.5, J=3.0, 3.5=K, etc.

Clarity Grade: 0=FL/IF, 1=VVS1, 2=VVS2, 3=VS1, 4=VS2, 5=SI1, 6=SI2, 7=I1

Comments: This is the "catch all" area for AGS certifications. Clarity characteristics that are not plotted are mentioned here. If a diamond has been enhanced by laser drilling, a comment will appear here as well. Surface or finish comments will also appear here for those diamonds that are equivalent to the GIA's Internally Flawless grade. If the diamond is laser inscribed, the inscription will be described here. The strength and color of the diamond's fluorescence, when exposed to long wave ultraviolet light, is noted in this section. The nomenclature is: negligible, medium, strong, very strong. Negligible replaced inert and faint effective January 1, 2003. The color of the fluorescence is only noted at strengths medium and greater.

Diamond Profile: This side view of a Round Brilliant diamond is where all the proportion information for each diamond is printed. The 100% figure represents the average diameter of a round stone and the width of a fancy shape. At a glance, the table %, crown height %, crown angle, girdle condition, minimum and maximum girdle thickness %, pavilion depth %, pavilion angle, culet size, culet condition (abraded or chipped), and total depth % are displayed in this section.

Plot: The crown and pavilion views of the plot are printed directly on the Diamond Quality Document. This feature is unique. Other laboratories have to use a peel and stick label. For Round Brilliant diamonds, the AGS Laboratories is able to print the crown view with the correct table diameter %. If a diamond has a 54% table, the crown view will show a 54% table. If the diamond has a 68% table, the crown view will show a 68% table.

Flap: The flap contains visual representations of the Cut, Color and Clarity Scales, as well as the Key to Symbols. The Color and Clarity Scales cross reference to equivalent GIA grades.

New AGS Cut Grades

American Gem Society Laboratories (AGSL) lab reports will include new and improved cut grades for round diamonds starting in the first quarter of 2005. For the first time, AGS will also offer a cut grade for princess cut diamonds. Round and princess cut diamonds constitute the most popular diamond cuts among U.S. jewelers and account for a majority of diamond sales. AGS cut-grading research is composed of an AGS task force as well as outside industry experts and physicists was started five years ago.

The format of the lab reports will remain the same as in the past, with final diamond grades listed on the familiar scale of 0 to 10. The changes incorporate the findings from advanced cut grade research on round brilliant diamonds and princess cut diamonds. The research findings enlarge by 37% the potential field of candidates for diamonds that can achieve a "0" grade (AGSL's highest cut grade for a diamond).

The new cut grade utilizes sophisticated ray-tracing software that measures dispersion by tracking how light moves through a diamond. The new round brilliant cut grade will be introduced in the first quarter of 2005. At the same time the AGS also plans to introduce cut grades for fancy shapes, including a cut grade for square princess cut diamonds. Rectangular princesses will be introduced in third quarter 2005. Other fancy shaped cut grades will be introduced in subsequent years.

AGS Certifications

Laboratory and Diamond Certificates Code

ADL	Antwerp Diamond Laboratory
AGA	American Gem Apraisal Laboratories
AGS	American Gem Society
CIB	CIBJO (Europe)
CSA	Jewellery Council of South Africa
DGL	Diamond Grading Laboratories (London)
EGI	European Gemmological Institute (Antwerp)
EGL	European Gemmological Institute (Antwerp & London)
GAG	Gesellschaft fur Angewandte Gemmologie
GAN	Gemological Institute of Antwerp
GIA	Gemological Institute of America
GII	National Gemological Institue of Israel
GIL	Gem Information Laboratory
GTL	Gem Testing Laboratory of Great Britain
HRD	Diamond High Council (Antwerp)
HRG	Heinz R Gartner, DGemG, FGA (Germany)
IGI	International Gemmological Institute (Antwerp)
NGL	Northern Gemmological Laboratories (UK)
PNF	P N Ferstenberg Pbv A
PSL	Precious Stone Laboratory (London)
VPT	Verena Pagel-Theisen, DGemG FGA (Germany)
WG	Werner Galia, DGem, (Germany)

GIA Certificate Sample

GIA Certificate Sample

Why buy GIA certified?

You probably already know that each diamond is qualified and priced according to the four "C's" (carat, color, clarity and cut). But have you ever wondered who grades the diamond a sales person shows you? In other words, how do you know a diamond shown to you as G color and VS1 clarity is really a G color, VS1 clarity diamond?
Let's assume that you purchase a diamond graded as 0.76 carats, G color and VS1 clarity from us at Five Star Jewelers. To ensure that our grading of the diamond is current, you decide to take it to ten different diamond appraisers, or graders. You will probably find that the ten appraisers give you at least six different combinations of grades, all of which might differ from the appraisal you received at Five Star. Does this mean that Five Star jewelers lied to you, and sold the diamond to you in an unethical or deceptive manner? Maybe Five Star's appraisal was valid and the other jewelers were giving you incorrect information. How can you compare diamond prices objectively if one diamond can receive any one of many subjective gradings?

Now you probably understand what a typical shopper has to go through in pursuit of that special diamond. Isn't there a better and simpler way of doing this? YES THERE IS! Shop for a diamond that has been certified, not by just anyone, but by the GIA(Gemological Institute of America). All diamond experts and jewelers know what a "GIA certificate" is. The GIA's grading is undeniably recognized throughout the jewelry industry as the most accurate and unbiased opinion when it comes to grading diamonds.

Comparing prices of diamonds with GIA certificates is now very easy. You don't even have to visit jewelry stores to make the comparisons. Simply call a jeweler and ask for a price on a GIA certified 0.76 carat, G color, VS1 clarity diamond with a good cut. If normal prices are competitive, they will be able to quote you an exact price. Then, all you have to do is buy the diamond from the jeweler with the best price. Theoretically, you would be able to reach a decision without even leaving home. Of course, factors other than price should also be considered. You will want to purchase a diamond from a jeweler who has a good reputation, quality workmanship, and solid guarantees.

It sounds easy, but who sells these GIA certified diamonds? Almost all jewelers sell them, even if many do not have them in stock. Many reputable jewelers sell nothing but GIA certified stones. You will even hear some jewelers tell you that their grading standard is as good as that of the GIA, so you don't really need a GIA certificate. Others will offer to send the diamond to the GIA for certification after you purchase it, which normally takes about one month. Some will tell you that GIA certified diamonds cost much more than non-GIA certified diamonds of the same grade (Actually, it costs only $98 to have the GIA certify a 1.0 carat diamond).

Some jewelers may inaccurately tell you that their diamonds are GIA certified. What they really mean is that their diamonds are graded by someone who graduated from a GIA grading course. Remember that the GIA is headquartered in Carlsbad, CA and their certificates come only from their New York and Carlsbad laboratories. Every diamond report from the GIA will have these addresses at the top of the certificate.

The only drawback to shopping for a GIA certified stone that we can think of is the limited availability of certain sizes and qualities. Generally, it is difficult to locate the following diamonds with GIA certificates:

1. Diamonds priced at less than $1,000
2. Diamonds with a weight less than 1/2 carat
3. Diamonds with clarities and colors lower than S12 and I, respectively.

Obviously, there will be some exceptions, so go ahead and make a few phone calls. You have nothing to lose.
The advantages of buying a diamond with a GIA certificate are:

1. You will know exactly what you are buying. Every important factor you need to know about the diamond is described in the certificate.
2. The seller knows exactly what he/she is selling to you so as to avoid any misunderstandings in the future.
3. If a diamond comes with a GIA certificate, you do not have to worry about the possibility that you might be purchasing a fracture-filled diamond. These are diamonds that have surface cracks that can be artificially filled to appear as much better diamonds than they actually are. These are in essence, very low quality diamonds that look great to naked eyes. GIA does not certificate these diamonds.
4. If a diamond comes with a GIA certificate, you will not become a victim of buying a synthetic diamond. Yes, there are real man-made diamonds that hit the market in 1977. Currently, average jewelers have no way of telling if a diamond is natural or man-made (These are not diamond stimulants as CZs, but real diamonds that are man made).
5. Purchasing a GIA certified diamond will simply provide you with much more confidence and value.

From : 4diamond.com

Diamond Certificates

A Diamond Grading Certificate should be considered as the diamond's "birth certificate." All of its characteristics, including the Shape, Colour, Clarity and Carat Weight are posted on it, along with specifications such as Polish, Symmetry, Girdle, Culet Size, and Fluorescence as well as the diamond dimensions. In addition to this, the location and position of each flaw and imperfection are also accurately mapped and shown on the certificate, so any trained gemmologist can tell immediately if the diamond you have purchased actually matches its certificate, and as an added safeguard, most diamonds now have the certificate number LASER inscribed onto the girdle (outer edge) of the diamond.



The above gemmological labs are amongst the most widely recognised in the industry, there are many others such as EGL, IGI etc but we tend to supply stones that have been independently certified by one of these three labs as a rule.

Diamond Certification

The importance of a diamond grading report is that it takes the guess-work out of buying a diamond. This report will "map" or plot the birthmarks of each diamond, which will allow you to identify your diamond forever.

The report will also detail carat weight, color, clarity, cut, and shape.

When you purchase a loose diamond, you should always be provided with a report from an independent gem lab. Be aware that many retail jewelers, including some of the biggest names in the business, create their own reports. These reports are graded with GIA methods, but are NOT done by the respected GIA, or EGL.

At Padis Gems we have every loose diamond graded by one of the following independent gem labs: GIA, or EGL.

One potential set back of using the GIA, is that it takes a very long time to get a stone back to the diamond dealer. Whereas the labs that we use have much faster turn around, which in the long run, saves you money.

What is GIA Certification?

An original GIA diamond grading report will have the Gemological Institute of America logo in the upper left. GIA GEM TRADE LABORATORY will be at the top of the document, with addresses and phone numbers, and the document will be laminated. The report will have a number. The position of this number will vary depending on the date issued. Recent documents have the number in the upper left hand corner under the GIA logo. Below that number will be the date of the document. Other places in which the report number will appear will often be to the right of the centered "DIAMOND GRADING REPORT" just below the addresses and the phone numbers of the lab.

Phony GIA certificates are known but they are quite rare and unusual. Very old certificates may have an LA or NY in front of the number. This indicates whether the document was created in the Los Angeles office or the New York office.

As an example of what you can expect to see on the old format certificate, the following sample GIA certification is illustrated.

GIA Certifications - Two Styles

The GIA currently has two styles of certifications, the Diamond Grading Report and the Diamond Dossier. Each certificate has a unique identification number that can be linked back to the grading laboratory's database.

Shape and Cutting Style details the style of cut for the diamond. There are many shapes including the Emerald and a variety of Brilliant Cuts (Round, Oval, Pear, Heart and Marquise). Many popular shapes are patented names and are not used on GIA certifications. For example, the Princess is described as a square modified brilliant, the Radiant is described as a rectangular cut-cornered modified brilliant and the Asscher is a square emerald.

Measurements are provided in millimeters to the hundredth of a millimeter and include length, width and depth. These measurements are taken with a millimeter gauge especially designed for measuring gems and jewelry. This information can be extremely helpful in protecting yourself from having your diamond "switched" in the future. It is very unlikely that anyone could find another diamond with the same three dimensions expressed to the hundredth of a millimeter.

Weight of a diamond is expressed in carats. A diamond scale is use to measure the weight of diamonds and is accurate to 0.01 carats.

Proportions describe various parts of the diamond in relation to other parts of the diamond. The Depth % is the ratio of depth to the average diameter. The table % is the ratio of the flat top (table) compared to the diameter. The girdle is the thin rim that separates the crown of the stone from the pavilion and is described in words that range from thin to extremely thick. The finish of the girdle (unpolished or faceted) will also be described. The Culet is the little facet at the very bottom of the stone and can range from large to non-existent. Large culets are generally considered unacceptable.

Finish indicates the grade of polish and symmetry of the stone. The symmetry describes how well the facets in the crown are aligned with the facets in the pavilion. For both polish and symmetry, it is desirable to be good, very good, or excellent.

Clarity Grade will be listed using the GIA grading scale. Only one clarity grade will be identified. If you see specifications for a diamond that have a range of clarity grades (VS2-SI1) or do not have the number in the grade (VS or SI), you know the diamond does not have a certification and the grades are suspect.

Color Grade will be listed using the GIA grading scale. Only one color grade will be identified. If you see specifications for a diamond that have a range of color grades (G-H), you know the diamond does not have a certification and the grades are suspect.

Fluorescence is a description of how ultraviolet light affects the diamond. About 50% of gem diamonds are fluorescent with about 35% having a level that impacts the appearance. Most fluorescence is blue, but other colors such as yellow, orange and green can appear. While no fluorescence is generally preferred, faint fluorescence can sometimes be a positive feature provided it isn't so strong that it makes the diamond look cloudy.

Comments are provided for those features of a diamond that a laboratory wants you to know but do not fit in the other specific categories. Most comments are minor and do not impact the value of the stone.

Plot of the diamond is the diagram of the internal inclusions and external blemishes as viewed with 10X magnification. The marks on the plot identify the location, size and type of flaws and very useful in the identification of your diamond. The plot becomes the fingerprint of the diamond and can be used to match the stone to the certification.

Source:www.diamondsourceva.com