Established in 1931, GIA is the world’s largest and most respected nonprofit institute of gemological research and learning.
GIA discovers (through GIA Research), imparts (through GIA Education), and applies (through the GIA Laboratory and GIA Instruments) gemological knowledge to the public. With 1,200 employees, the Institute’s scientists, diamond graders, and educators are regarded as the world's foremost authorities in gemology.
Internationally, the Institute has distinguished itself as the preeminent source of gemological knowledge and professionalism. The GIA Diamond Grading Report and the GIA Diamond Dossier® are considered to be the world's premier credentials of diamond quality. Many retailers provide diamond certification, however no report is as unbiased and complete as a GIA diamond grading report. Diamonds of all shapes and sizes are sent to the Institute from every corner of the globe for diamond grading and analysis.
Some famous diamonds have been graded by GIA including the Hope Diamond (45.52 carats), the Steinmetz Pink (59.60 carats), the Taylor-Burton (69.42 carats), the Allnatt (101.29 carats), the De Beers Millennium Star (203.04 carats), the Centenary (273.85 carats), and the Incomparable (407.48 carats).
GIA is the creator of the revolutionary 4Cs of diamond value (carat, color, clarity, and cut). It is also the birthplace of the International Diamond Grading System™. Today, GIA’s D-Z color-grading scale, Flawless–I3 clarity-grading scale and Excellent-to-Poor cut-grading scale are recognized by virtually every professional jeweler and savvy diamond buyer in the world
Locations and Research Facilities
Gemological Institute of America
The Robert Mouawad Campus
5345 Armada Drive
Carlsbad, California 92008
To schedule a museum and exhibit tour,
Call: 800-421-7250 ext. 4116 or 760-603-4116
GIA Laboratory Headquarters
580 Fifth Avenue, Suite 200
New York, New York 10036
West Coast Laboratory
5355 Armada Drive
Carlsbad, California 92008-4699
10th Floor, U-Chu-Liang Building
968 Rama IV Road
The Robert Mouawad Campus
5345 Armada Drive
Carlsbad, California 92008
GIA New York
New York Education Center
270 Madison Ave., 2nd Floor
New York, NY 10016-0601
GIA Los Angeles
600 Corporate Pointe, Suite 100
Culver City, California 90230
Piazza Santa Trinita, 1
50123 Firenze, Italy
GIA Japan - Osaka
3F Nagahori Community Bldg.
2-5-8 Minamisenba, Chuo-ku
BiscoTower - 12th Floor
56/12-13 Sub Road
Si Phraya, Bangrak
Bangkok, 10500 Thailand
104 Great Russell Street
Tel: 44 20 7813 4321
Fax: 44 20 7813 4331
Miklukho-Maklaya Street, 23
117997 Moscow, Russia
92, 9th Floor
Maker Chambers VI
GIA Hong Kong
Rm 301, 3/F, Aon China Building
29 Queen's Road Central,
GIA Japan - Tokyo
2-3F Okachimachi, CY Bldg.
5-15-14 Ueno, Taito-Ku
Tokyo, Japan 110-0005
GIA Korea - Seoul
Keuk Dong Bldg. 5th Floor
Kangnamku, Sinsadong 639-3
3F, 270 Nanjing East Road, Sec. 3
19 Xiao Huang Zhuang Road
Beijing, P.R. China 100013
A Guide to Understanding Diamonds and GIA Grading Reports
GIA wants you to understand exactly what you’re buying when shopping for your diamond. As creators of the 4Cs and the International Diamond Grading System™, GIA set the standards for diamond grading and has been helping consumers make educated diamond buying decisions for over 50 years.
GIA’s D-to-Z color-grading scale, Flawless-to-I3 clarity-grading scale, and Excellent-to-Poor cut-grading scale are all recognized by gem and jewelry professionals everywhere. And, by extension, the GIA Diamond Grading Report, Diamond Dossier®, and Gemological Identification Report are considered to be the world’s premier evaluations of gem quality and authenticity.
How did the 4Cs of Diamond Quality Come to Be?
The Four Cs of diamond quality will give you a multitude of information about a diamond’s characteristics and value, but they can’t begin to describe one elusive quality – beauty. To do that, you’ll need to experience the diamond with your own eyes.
Carat weight is the most intuitive of the 4Cs – you expect a larger diamond to be worth more when assigning diamond values.
Because even a fraction of a carat can represent a considerable difference in cost when purchasing diamonds, exact precision is crucial. In the diamond industry, weight is measured to a thousandth of a carat and rounded to the nearest hundredth. Each hundredth is called a point (a 0.25 ct. diamond would be called a “twenty-five pointer”). Diamond weights greater than one carat are expressed in carats and decimals. (For instance, a 1.08 ct. stone would be described as “one point oh eight carats,” or “one oh eight.”)
The Color of the diamond is all about what you can't see.
GIA's diamond color-grading scale is the industry’s most widely accepted grading system. The scale begins with the letter D, representing colorless, and continues, with increasing presence of color, to the letter Z. Diamonds are color-graded by comparing them to stones of known color under controlled lighting and precise viewing conditions.
Many of these color distinctions are so subtle that they are invisible to the untrained eye. But these slight color differences make a very big difference in diamond quality and price.
Diamond Clarity refers to the absence of internal inclusions or external blemishes.
Every diamond is unique. But none are absolutely perfect even though some come close, even under 10x magnification. Known as flawless diamonds, they are exceptionally rare. Most jewelers have never even see one.
The GIA Clarity Scale contains 11 grades, with most readily available diamonds falling into the VS or SI categories. In determining a clarity grade, GIA considers the size, nature, position, color or relief, and quantity of clarity characteristics visible under 10x magnification.
- Flawless (FL)
No inclusions or blemishes are visible to a skilled grader using 10× magnification
- Internally Flawless (IF)
No inclusions and only minor blemishes are visible to a skilled grader using 10× magnification
- Very, Very Slightly Included (VVS1 and VVS2)
Inclusions are difficult for a skilled grader to see under 10× magnification
- Very Slightly Included (VS1 and VS2)
Inclusions are clearly visible under 10× magnification but can be characterized as minor
- Slightly Included (SI1 and SI2)
Inclusions are noticeable to a skilled grader using 10× magnification
- Imperfect (I1, I2, and I3)
Inclusions are obvious under 10× magnification and may affect transparency and brilliance
Cut fuels the diamond’s fire, sparkle, and brilliance.
Though extremely difficult to analyze, the cut of a diamond has three attributes: brightness (the total light reflected from a diamond), fire (the dispersion of light into the colors of the spectrum), and scintillation (the light flashes – or sparkle – when a diamond moves).
An understanding of diamond cut begins with the shape of a diamond, with the standard round brilliant dominating the majority of diamond jewelry. All other diamond shapes are known as fancy shapes or fancy cuts and include the marquise, pear, oval, and emerald cuts. Hearts, cushions, triangles, and a variety of other new shapes are also gaining popularity in many forms of diamond jewelry.
As a value factor, though, cut refers to a diamond’s proportions, symmetry, and polish. For example, look at a side view of the standard round brilliant. The major components, from top to bottom, are the crown, the girdle, and the pavilion. A round brilliant cut diamond can have either 57 or 58 facets, the 58th being a tiny flat facet at the bottom of the pavilion, known as the culet. The large, flat facet on the top is the table. The proportions of a diamond refer to the relationships between table size, crown angle, and pavilion depth. A wide range of proportion combinations are possible, and these ultimately affect the stone’s synchronicity with light.
In early 2005, GIA unveiled a diamond cut grading system for standard round brilliants in the D-to-Z color range. This system, the product of more than 15 years of intensive research and testing, assigns an overall diamond cut grade ranging from Excellent to Poor.
More About Diamonds and Purchasing from a Trusted Partner
There is nothing inherently unethical about treating a diamond, but U.S. law requires full disclosure. GIA’s research efforts have been critical in identifying each of the diamond treatment techniques described here and is committed to helping the gem-buying public know exactly what they’re buying.
More About Diamonds: Treated Diamonds
Diamond Color EnhancementThe oldest technique to enhance a diamond’s color is to coat it. Not as common as it once was, this sophisticated process uses ultra-thin layers of chemicals or plastics to enhance a diamond’s color. Today, most coated diamonds are easily detectable under magnification.
Irradiation induces a permanent color change throughout the entire stone. The post–World War II atomic age saw an influx of artificially irradiated diamonds.
HPHT stands for a High Pressure, High Temperature, a laboratory process which can be used to change the color in some gem diamonds. In the 1990s, scientists began to experiment with ways to modify diamond color using this technique. HPHT treatment can change the color of certain diamonds, making them colorless, pink, blue, green, yellowish green, or yellow.
Diamond Clarity EnhancementTwo techniques for improving a diamond’s clarity are laser drilling and fracture filling. Both of these clarity enhancements are easily detected with magnification and suitable lighting.
Laser drilling is used to remove small, dark inclusions. The laser bores a small hole into the diamond’s interior and burns away the inclusion, leaving behind a tiny drill hole.
Fracture filling hides white areas which are called “feathers.” A glass-like substance is injected into the fracture to make it less visible, improving the stone’s clarity by one or even two diamond quality grades. But because it is not stable to all routine cleaning and repair techniques, the technique has been quite controversial.
Conflict Diamonds and the Kimberly Process for Diamond Certification
In 2000, industry organizations began working with world governments, human rights groups, and the United Nations to create the Kimberley Process Certification Scheme, aimed at removing undocumented rough diamonds from the marketplace. According to this system, all rough diamonds had to be accompanied by a diamond certificate of origin issued by an approved agency. From that point, all the way to the consumer, it became mandatory that each diamond be accompanied by a document confirming its legitimate pedigree.
Unfortunately, the place where a diamond is found, and the fact that they can travel hundreds of miles from their true point of origin, makes it virtually impossible to know where a specific diamond originated. Because GIA only reports on what it knows, it does not report on point of origin.
The Kimberley Process took effect on January 1, 2003 and, by all accounts, it appears to be working. With the end of civil war in Angola and Sierra Leone, peace and stability have returned to those countries.
Early attempts to synthesize diamonds date all the way back to the nineteenth century. But the process of duplicating the extreme heat and pressure under which natural diamonds are formed was elusive. In 1955, General Electric overcame these technological barriers and produced small, industrial-quality stones – the first synthetic diamonds. Since then, the processes of synthesizing diamonds have gotten better and better.
Gem-quality synthetic diamonds have been available to consumers since the mid-1980s. While they represent a small segment of the market, they are becoming more widespread and increasingly difficult to detect when purchasing diamonds. GIA is at the forefront in meeting this challenge, giving a distinct report for synthetics so that there is no confusion in the marketplace.
Some of the oldest diamond imitators were made of glass, garnet and glass doublets, rhinestones, and synthetic sapphire. But probably the most familiar simulant is the cubic zirconia. Known by the household name “CZ,” it is nearly as brilliant, shimmering, and durable as a diamond.
In 1997, a stone called synthetic moissanite entered the market, closely resembling a diamond. It shared many of the same optical and physical characteristics but what really invoked controversy was that it fooled the thermal testers used to detect previous diamond simulants.
No matter how convincing it may seem, any diamond simulant will have optical or physical characteristics that can be identified by a trained gemologist. In the case of synthetic moissanite, double refraction is a dead giveaway. When you look through a large facet, you’ll see a doubling of facet junctions on the opposite side of the stone.
But even a diamond isn’t indestructible. It can be chipped by a sharp blow or become loose in its setting and fall out. A diamond should be worn with care.
Because diamonds tend to pick up grease and oils, they can become dirty with handling and should be occasionally wiped with a lint-free cloth. Other methods for safe cleaning include warm water, mild soap, and a soft toothbrush or a commercial cleaning solution. It is not recommended to use ultrasonic and steam cleaners.
GIA Grading & Reports
GIA Diamond Grading & Reports
For stones between 0.15 and 1.99 carats, GIA offers the Diamond Dossier® It contains the same information found on the traditional diamond grading report but in a more compact format. As an added security measure, the Diamond Dossier® includes a laser inscription of the identification number. A professional jeweler can arrange to have your diamond graded.
GIA’s laser inscription service can also be used for personal messages and anniversary dates. At the client's request, a diamond may be microscopically inscribed on its girdle with its unique GIA Report Number (referred to as the GIA Inscription Registry), a personal message, or other text, symbols, or logos. An inscription allows for easy identification of a diamond, a way to personalize the diamond, or serves as a form of branding for the diamond manufacturer or retailer.
GIA Grading & Reports
Why Get a Diamond Grading Report?
A Diamond Grading Report isn’t an appraisal but a scientific blueprint of your stone’s exact qualities. GIA’s heritage as a research and educational institution means they are trusted to provide accurate, unbiased diamond evaluations. All GIA diamond grading reports contain a hologram, a security screen, and microprint lines as well as other security features that exceed industry guidelines. Simply put, they’re here to help you know what you’re buying.
A GIA grading report provides an expert analysis of a diamond’s quality based upon the “4Cs” of diamond grading: carat, color, cut and clarity. The GIA Diamond Grading Report also contains a plotting diagram that clearly shows the diamond’s unique inclusions and other clarity characteristics such as inclusions. It undergoes a technical screening process, determining its potential as a synthetic or diamond stimulant and is tested to ensure that the color is natural. Because GIA is not affiliated with any commercial enterprise, impartial and accurate analysis of a diamond’s quality and value is assured.
GIA employs hundreds of highly trained diamond graders, gemologists, research scientists who scrutinize the diamonds and analyze them, depending on size, with as many as 40 pairs of eyes for each stone. GIA Laboratory experts have graded some of the world’s most famous diamonds, including the legendary Hope Diamond (45.52 carats) and the De Beers Centenary Diamond (273.85 carats).
Colored Diamonds, Gemstones and Pearls
The physical conditions necessary to color a diamond naturally occur very seldom, making natural color diamonds extremely rare. For every natural color diamond, there are 10,000 colorless ones that have made the trip from the earth’s depths to its surface. It is this entirely natural process of geographical formation which ensures that each natural color diamond is one of a kind.
The formation of natural color diamonds is a process that requires the presence of additional trace elements and distortions to the typical diamond crystal. During the creation of a diamond, if an element interacts with its carbon atoms, the color can change. Natural radiation and pressure on a diamond’s structure can also intensify its color.
Rather than emphasizing the brilliance and fire coveted in near-colorless diamonds, these stones are all about the color intensity. The Argyle mine in Western Australia launched a massive marketing campaign some time ago that helped change the public’s perception of these previously overlooked diamonds. The 1987 sale of the Hancock Red, at a record auction price of $926,000 per carat, further magnified the allure of fancies.
Color Grading of Fancy DiamondsGIA’s system for color-grading colored diamonds was developed in the mid-1950s and revamped in the mid-1990s. The diamond color grading system expresses color using the attributes of hue (the characteristic color), tone (the color’s relative lightness or darkness), and saturation (the strength or weakness of the color). Using controlled viewing conditions and color comparators, the grader determines the stone’s color from one of 27 hues. The fancy grade describes the stone’s tone and saturation with romantic names like “Fancy Light,” “Fancy Intense,” and “Fancy Vivid.”
Today, the GIA color grading system for colored diamonds is used worldwide. Many of the most famous colored diamonds, including the Blue Hope, the Dresden Green, and the Hancock Red, have been examined by the GIA laboratory using GIA’s color grading system.
GIA offers two types of diamond grading reports for colored diamonds. The GIA Colored Diamond Grading Report contains the same comprehensive diamond information as the GIA Diamond Grading Report. In addition, the GIA Colored Diamond Identification and Origin Report, known as the color-only report, gives a color grade and the nature of the color.
Colored GemstonesWhile renowned for its diamond grading expertise, the GIA Laboratory also receives a vast array of colored gemstones for identification—and its work in this area has been equally remarkable. Over the decades, the Institute has created a database of information on more than 100,000 individual gemstones. Using this database and sophisticated analytical tools, GIA researchers can pinpoint a gem’s identity, and depending on the gemstone, even it's geographic orgin. They also distinguish synthetics, simulants, and stones that have undergone treatment. A particularly important activity involves determining the origin of color in gemstones—whether it is natural or the result of a treatment process.
The GIA Laboratory applies the same item identification and tracking procedures to colored stone identification as it does to diamond grading.
Pearl IdentificationOver the past 100 years, discoveries in pearl culturing have revolutionized the industry, all but completely replacing natural pearls with cultured pearls. By the end of the 20th century, several types of cultured pearls were being produced in an overwhelming variety of colors, shapes, and sizes.
In response, GIA sought to create a standard for pearl grading and terminology—much as it had with diamonds in the 1950s. Its pearl-grading system, launched in 1998, was based on GIA's 7 Pearl Value Factors™: size, shape, color, luster, surface quality, nacre quality, and matching.
Feel Confident with the GIA Diamond Buying GuideBuying a diamond can be a significant purchase both emotionally and financially, but it doesn’t have to be intimidating. Here are four basic steps to ensure that the journey to find the perfect diamond for you is as pleasurable as admiring the diamond you finally select.
1. Choose your qualified diamond jeweler just like you would choose your doctor, lawyer, or any other professional. Ideally, your jeweler is a GIA-trained Graduate Gemologist (G.G.) or Accredited Jewelry Professional (A.J.P.) and is affiliated with jewelry industry groups and professional associations such as the American Gem Society (AGS) and American Gem Trade Association (AGTA). A knowledgeable jeweler will clearly explain the 4Cs of diamond quality and encourage you to compare a number of diamonds that fall into your price range.
2. Learn the 4Cs of diamond quality, the key to a diamond’s value and subsequent price.
CaratDiamonds are weighed in carats with one carat weighing about the same as a paper clip, or 0.2 grams. Just as a dollar is divided into 100 pennies, a carat is divided into 100 points which means that a diamond of 50 points weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on their clarity, color, and cut. Carat weight is the most intuitive of the 4Cs – you expect a larger diamond to be worth more.
ClarityBecause they are created deep within the earth, most diamonds contain unique birthmarks called inclusions (internal) and blemishes (external). Diamonds without these clarity characteristics are rare – and rarity translates to higher cost when purchasing diamonds. Using the GIA Diamond Grading System, diamonds are given a clarity grade that ranges from Flawless to Included (I3).
ColorColorless diamonds are extremely rare and very valuable - most are nearly colorless with yellow or brown tints. The GIA Diamond Grading System uses letters to represent colors, beginning with D (colorless) and ending at Z (light yellow or brown). Many of these color distinctions are so subtle that they are invisible to the untrained eye but these slight color differences make a big difference in price.
CutWhile diamonds come in many different shapes, including round brilliants, hearts, pears , and marquises, cut has to do with proportion and the arrangement of facets. The sheer beauty of a diamond depends on cut more than anything else, using light to create brilliance, sparkle, and flashes of fire. The GIA Cut Scale ranges from Excellent to Poor. GIA provides a cut quality grade for standard round brilliant diamonds that fall in the D-to-Z color range.
3. Get your diamond reports. Insist that your diamond come with grading report or, for other gemstones, an identification report from an independent, accredited gemological laboratory like GIA - your assurance of value, quality, and authenticity. GIA Diamond Grading Reports are the most widely used reports in the industry and offers laboratory grading services and reports directly to the public. Since GIA only grades unmounted diamonds, they recommend working with your jeweler so that your diamond is submitted correctly.
4. Keep your purchase secure. Before you surprise your love with a piece of diamond jewelry, have the piece appraised and insured. Appraisers and insurers rely on diamond grading and identification reports to accurately evaluate the quality and value of gems.
The GIA Laboratory can also laser-inscribe the diamond’s unique Diamond Grading Report number to provide verification if the diamond is ever lost or stolen. Or, if you prefer, personalized messages can be inscribed. Your local jeweler can help you with this request or you can contact GIA directly.
Engagement Ring Buying GuideYou’ve captured her heart. Now tell the world with the perfect diamond engagement ring. Purchasing a diamond engagement ring is an exhilarating experience, but it is important to be informed before you decide on which ring best expresses your love.
To understand exactly what you are buying, start with an unbiased, scientific evaluation like a GIA diamond report from the organization that set the international diamond grading standard. Diamonds may look alike. A GIA report will reveal the difference.
Be sure to consult with a quality diamond jeweler. Their expertise will go a long way towards guiding you in the world of diamond buying. And, above all, don’t let the dizzying array of choices confuse you. Simply take a good look at the jewelry she wears on a daily basis. Is it mostly gold or silver? Contemporary or traditional? If you buy something similar to what you already know she likes, you can’t go wrong.
Your budget also plays a large role in determining which ring you’ll end up choosing. The standard rule is two months salary but this is only a place to start. While jewelers will sell you a preset ring, you can often get a more exquisite piece of jewelry for your money if you choose the diamond first and then decide on the setting.
Depending on what you order, it could take a couple weeks or more to have the stone set, do any engraving, or custom design your ring. So if you want to propose on a certain date, make sure you start working on the diamond engagement ring early.
Below are a few popular setting styles:
Solitaire SettingSolitaire Setting is a popular diamond engagement ring setting. The head secures the diamond. The prongs allow the diamond to catch the most light. A four-prong setting shows more of the diamond, but a six-prong setting is often more secure.
Settings with SidestonesSettings with Sidestones, such as diamonds or gemstones, add additional sparkle or color. Popular sidestone settings are Channel, which protects stones by keeping them flush, and bar-channel, which allows more light to enter the sidestones.
Three-Stone SettingsThree-Stone Settings have one diamond for the past, one for the present, and one for the future. Typically the center diamond is larger than the two side stones.
Helpful Resources for Buying Diamonds
Insuring high-value personal property is a good idea, and your jewelry is no exception. Homeowner's and renter's insurance policies usually offer full coverage for jewelry theft, but not necessarily damage or loss. Carefully review your policy. Depending on the value of your collection, you might consider insurance specifically for your jewelry. Ask whether this policy would cover unset gemstones and antique jewelry.
Learn about Appraisals
While GIA can’t recommend an individual appraiser, there are several appraisal associations and networks that can help you locate one in your area. These are national associations that have members all over the country, and many require that their appraisers have a Graduate Gemology (G.G.) diploma from GIA in addition to supplemental appraisal training.
In the United States
American Gem Society
8881 West Sahara Ave.
Las Vegas, NV 89117
American Society of Appraisers
555 Herndon Parkway #125
Herndon, VA 20170
(703) 478-2228 or (800) 272-8258
Appraisers Association of America, Inc.
386 Park Ave. S. #2000
New York, NY 10016
The Jewelry Judge Network
Telephone: (866) 558-3431
Outside the United States
Accredited Appraiser Program
Canadian Jewellers Association
600 – 27 Queen Street East
Toronto, Ontario, Canada M5C 2M6
Toll free (800) 580-0942
Diamond Pricing Guides
GIA does not comment on the value of gemstones but there are several companies that publish pricing guides for diamonds and colored stones.
The Diamond Registry® Bulletin
580 Fifth Avenue, Suite 806
New York, NY 10036
Diamond prices only
Gemworld International, Inc.
630 Dundee Road, Ste. 230
Northbrook, IL 60062
(847) 564-0555 or (888) 436-4843
Diamond and colored stone prices
Michelsen Gemstone Index
Center for the Study of Gemstone Evaluation
P.O. Box 1782
Port Angeles, WA 98362
Diamond and colored stone prices and estimated fancy-color diamond prices
Polygon Network, Inc.
P.O. Box 4806
Dillon, CO 80435
(800) 221-4435 (Sales)
Diamond and colored stone prices
Rapaport Diamond Report
1212 Avenue of the Americas
New York, NY 10036
Diamond prices only
Michael Goldstein, Ltd.
580 Fifth Ave, Ste 903
New York, NY 10036
Antique-cut diamond price guide