Fact Sheets

These fact sheets have been compiled to provide some basic background on gemstones, GIA, and the services the Institute provides. Please do not hesitate to contact us for more information.


  • Diamonds

    What is a Diamond?

    • Diamond is a mineral composed of a single element: carbon.
    • Diamond is the most durable gemstone, and even considered the hardest natural substance on earth.
    • Diamond has a hardness of 10 on the Mohs scale, a refractive index of 2.417, a dispersion of 0.044 and a specific gravity of 3.52. Its luster is adamantine.
    • A diamond forms in the cubic, or isometric, crystal system. It has four directions of perfect octahedral cleavage and shows a step-like fracture surface.
    • A diamond’s color ranges from colorless to yellow, brown, gray, orange, green, blue, white, black, purple, pink and (extremely rarely) red.
    • Diamonds were formed millions of years ago, approximately 100 miles below the earth’s surface.
    • Diamond crystals were brought to the earth’s surface through volcanic activity.
    • Less than 20 percent of the diamonds mined worldwide are gem-quality.
    • The earliest written account of diamonds dates back to around 500 B.C.
    • Diamonds are virtually fireproof. To burn a diamond, it must be heated to 1292°F.
    • Only one polished diamond out of a thousand weighs more than a carat.
    • The word carat comes from the Mediterranean carob tree, whose seed was used for centuries as the standard of weighing precious stones. 1 carat = .2 grams, or .007 ounces.
    • The largest rough diamond, discovered in 1905, is the Cullinan diamond, weighing in at 3,106 carats (2.8 lbs).

    What are the “Four C’s” of diamond quality?

    • A diamond’s rarity is determined by its unique characteristics, as measured by the Four C’s: Cut, Color, Clarity and Carat Weight. Using these criteria, a small diamond of exceptional quality will likely be more valuable than a larger diamond of lower quality.
    • Carat Weight - Diamonds are weighed in metric carats. A carat weighs about the same as a paperclip. Just as a dollar is divided into 100 pennies, a carat is divided into 100 “points.” In other words, a 50-point diamond weighs 0.50 carats. But two diamonds of equal weight can have very different values depending on their clarity, color and cut.
    • Clarity - Diamonds are created by nature, and most contain unique birthmarks called “inclusions” (internal) and “blemishes” (external). Diamonds with few birthmarks are rare—and rarity affects value. Using the internationally recognized GIA Diamond Grading System, diamonds are given a clarity grade that ranges from flawless (F) to highly included (I3).
    • Color - Colorless diamonds are extremely rare and highly valued. Most diamonds are nearly colorless, with yellow or brown tints. The GIA Diamond Grading System uses letters to represent color, beginning with D (colorless) and ending at Z (light yellow or brown). If a stone shows a natural color slightly deeper than Z, its color is designated as "fancy." GIA uses a separate color system to grade fancy-color diamonds.
    • Cut - The fact that there are 58 tiny facets in a traditional round brilliant diamond, each carefully cut and sharply defined, might seem nothing short of miraculous. But this precision is essential to the potential beauty of a diamond. As a matter of fact, overall appearance – the brilliance, fire and scintillation that makes a diamond uniquely beautiful – depends more on cut than anything else. The GIA Diamond Cut Grading System, introduced in 2005 after years of extensive research, assigns one of five grades to describe the overall cut quality of a standard round brilliant diamond in the GIA D-to-Z color range.

    Visit the Library for more diamond information.

  • GIA Laboratory

    What Sets GIA Apart from other Labs?

    • The GIA Laboratory is part of a nonprofit education and research institute dedicated to the study and the advancement of gemological science. Four world-class research laboratories, located in Carlsbad, New York, Antwerp and Bangkok, provide GIA with the scientific expertise and state-of-the art instrumentation to identify and readily detect treatments, synthetics, and gemstone simulants.
    • Grading and identification records are archived in an extensive global database for ongoing study and future reference. This also gives us the ability to identify items that have been submitted previously to the Laboratory, and assist law enforcement in the recovery of stolen goods.
    • Compliance – Besides adhering to the most stringent grading standards, GIA operates under a strict code of ethics designed to ensure the objectivity and integrity of its reports and services.
    • Nonprofit status – Revenue is continually reinvested in GIA research and education efforts.
    • Online services – Through “My Laboratory,” clients have secure, 24/7 access to their GIA Laboratory accounts to check the current status of their diamonds or colored stones.
    • Gemological Expertise - Our laboratory experts are GIA Graduate Gemologists and have years of training and experience in the lab as well as in the trade. Laboratory managers and directors have between 15 and 30 years of grading and gemstone identification experience at GIA. We also employ many world-renowned industry experts and multidisciplinary scientists.

    In addition, GIA:

    • Developed the diamond quality grading system, and is the only laboratory that owns the original diamonds that determined current color grading standards.
    • Created a system to describe the color of fancy colored diamonds, and is in the process of developing a quality grading system for natural and cultured pearls.
    • Has graded most of the world’s significant diamonds in terms of size, quality and market value
    • Has more than 50 years of experience identifying all types of diamonds, colored stones and pearls

    Who are our main customers?

    • The majority of our customers come directly from the gem and jewelry trade. We are proud to serve them, as well as the public at large.

    How many laboratory locations (including take-in windows) do we have and where are they?

    • We currently provide laboratory services from locations in: California, New York, Mumbai, Bangkok, Johannesburg, and Hong Kong. GIA Lab Direct, our network of authorized third-party consolidators, offers take-in services in Israel, India, Belgium and Japan.

    Laboratory Highlights

    • During its early years, GIA created the “Four C’s” of Color, Carat Weight, Clarity and Cut, now universally recognized as the factors determining diamond quality.
    • Based on the Four C’s, GIA also created the International Diamond Grading System, introduced in 1953 and now used by nearly every jeweler around the world.
    • GIA issued its first diamond grading reports in 1955.
    • In 2005, GIA introduced a cut grading system for standard round brilliant cut diamonds, based on the relationship of the proportions of the diamond to its face-up appearance.
    • GIA has the reputation of having the strictest and most uniform grading practices of all gem grading laboratories.
    • The first GIA Laboratory was set up by Robert Shipley—in his home, with borrowed equipment—in 1931. In the early years, the lab primarily did pearl and colored stone identification.
    • GIA now has laboratories in Carlsbad (California), New York, Mumbai, Bangkok and Johannesburg.
    • GIA has graded some of the world’s most famous diamonds: the Hope, Heart of Eternity, Millennium Star, Tiffany, Premier Rose and Incomparable, to name a few.
    • Each gemstone sent to the Laboratory is examined to determine whether it is natural, synthetic, imitation or treated.
    • The Institute’s diamond graders and gemologists examine a diamond by the Four C’s: color, clarity, cut and carat weight. Colored gemstones and pearls have different grading systems.
    • For loose, natural diamonds that fall within the D-to-Z color scale, GIA offers a Diamond Grading Report and a Diamond Dossier (for stones between 0.15 and 1.99 carats). For round brilliants, a diamond cut grade is optional with both reports.
    • In 2007, GIA began offering diamond grading services for synthetic diamonds to protect the public from any undisclosed goods coming into the market.
    • GIA offers a special Cut grade for standard round brilliant cut diamonds falling in the GIA D-to-Z color sale and Flawless-to-I3 clarity scale. These reports also contain illustrations of the diamond’s actual proportions along with expanded proportion data.
    • Take a closer look at GIA Report.

  • Grading & Identification

    Grading & Identification Services Fact Sheet

    • For a polished diamond, GIA provides the following services:
      • Diamond quality grading: GIA Diamond Grading Report™ or the GIA Diamond Dossier®
      • Colored diamond quality grading
      • Colored diamond identification and origin of color (natural or treated color)
      • Synthetic diamond grading
      • Synthetic colored diamond grading*
      • Synthetic diamond identification
      • Laser inscription of a microscopic identifying mark or personal message on the girdle of a gemstone (GIA Report Number inscription is included with the GIA Diamond Dossier® and the Synthetic Diamond Report)
      • Diamond type analysis (type Ia, IIa, Ib, IIb)
      • Damage analysis, to determine if physical damage has occurred since the item was last polished
      • Master color comparison set for diamond grading
    • All natural and synthetic diamond services include identification of the item as well as the detection of color or clarity treatments. Also upon request at no additional charge, we offer an evaluation of the clarity status—whether the clarity grade could be improved through minor recutting of the diamond. If improvement is possible, a report sleeve is provided that includes a diagram indicating the clarity characteristics that would need to be minimized.
    • GIA Report Check is an online report verification service for GIA Diamond Grading Reports and Diamond Dossiers issued after 2000.
    • For colored gemstones and pearls, GIA provides gemstone identification, geographic origin when possible, damage analysis and detection of treatment, synthetics and imitations.
    • In addition, GIA offers secure and confidential online services for lab clients with “My Laboratory.” This service allows clients to check the current status of items submitted to GIA, view grading results, and request additional services.

  • Pearls

    Pearls Fact Sheet

    • Pearls—and their modern counterparts, cultured pearls—occur in a wide variety of colors. 
    • Perhaps the most familiar colors are white and cream, along with black and gray, but pearl colors extend to virtually every hue. 
    • Natural pearls are organic gems that form inside the shells of certain mollusks, usually around a microscopic irritant without any human intervention. Once more prevalent, natural pearls virtually disappeared from the mainstream jewelry market during the twentieth century.
    • Cultured pearls are grown with the help of humans. Technicians insert nuclei (usually shell beads or pieces of flesh from other mollusks) into each mollusk. These act as the irritants that stimulate pearl growth.
    • Cultured pearls have been commercially produced since the early twentieth century, when Japanese pioneers began growing whole cultured pearls.
    • Japan has been joined by several other cultured pearl–producing countries, including China, French Polynesia, Australia, Indonesia and the Philippines.
    • Pearls have a hardness of 2½ to 4 on the Mohs scale, which means they are very soft and easily scratched.
    • High heat can cause discoloration, splitting or cracking. 
    • The primary treatments for improving pearl color are bleaching, dyeing and irradiation.
    • Pearl, natural or cultured, is a U.S. birthstone for June.
    • GIA offers Identification Reports for Pearls, specifying the weight, size, shape, color, origin (natural or cultured and type of nucleation), mollusk (if determinable), environment (saltwater or freshwater), and any detectable treatments. In addition, GIA also Classification Reports which include all of the information above, plus luster, surface, nacre thickness and matching (if applicable).

    Visit the Library for more information about pearls.

  • Sapphire

    Sapphire Fact Sheet

    • A sapphire is one of the two gem varieties of the species corundum.
    • Although blue is the best known hue, the gem occurs in virtually every spectral hue excepting red; red corundum is ruby.
    • Sapphire may also be colorless, and it also occurs in the non-spectral shades gray and black.
    • Sapphire is the birthstone associated with September.
    • More than two dozen places around the world produce sapphires, but the most famous historical source is the Kashmir region, which lies between Pakistan and India, as well as Burma and Sri Lanka.
    • Today the major sapphire sources are Madagascar, eastern Africa, Sri Lanka and Australia, Cambodia and the U.S.
    • Some sapphires are “star sapphires,” that literally show a star of light across the top of the stone.
    • Sapphires and rubies are made of the same core mineral: corundum
    • There are synthetic sapphires made today
    • For centuries, sapphire has been associated with royalty and romance. The association was reinforced in 1981, when Britian’s Prince Charles gave a blue sapphire engagement ring to Lady Diana Spencer.
    • Not all sapphires are blue. Fancy sapphires, as they’re called, come in violet, green, yellow, orange, pink, purple, and intermediate hues. Sapphires can even be gray, black or brown. 
    • Clergy in the late Middle Ages favored blue sapphire for their ecclesiastical rings because its color symbolized heaven.
    • People took sapphire as an antidote for poison and poisonous bites. They belied the stone could clear the mind and skin and cure fevers, cold and ulcers.

    Visit the Library to learn more about sapphires.

  • Ruby

    Ruby Fact Sheet

    • A ruby is a pink to red gemstone, a variety of the mineral corundum.
    • The common red color is caused mainly by the presence of the element chromium.
    • Ruby and sapphire come from the same material, corundum, but each are colored by trace elements of different minerals.
    • Its name comes from ruber, which is Latin for red.
    • Ruby is the birthstone associated with July.
    • People discovered rubies early in written history. Rubies are mentioned in the Old Testament and ancient Sanskrit texts.
    • Because it was red, people thought rubies could cure blood disorders or heal wounds.
    • Burma, Madagascar, Sri Lanka, Thailand, Cambodia and Vietnam, Afghanistan, Kenya, Malawi and Tanzania produce rubies.
    • People in India believed that rubies enabled their owners to live in peace with their enemies.
    • In Burma, warriors wore rubies to make themselves invincible in battle.

    Visit the Library for more information on rubies.

  • Emerald

    Emerald Fact Sheet

    • Emerald is famous for its deep, distinctive green color.
    • Emeralds are a variety of the mineral beryl, colored green by trace amounts of chromium and sometimes vanadium. Other beryl varieties include aquamarine and morganite.
    • The first known emeralds emerged from the mines of ancient Egypt perhaps from at least 330 BC in the 1700s. Cleopatra was known to have a passion for emerald, and used it for her royal adornments.
    • Emeralds are regarded as the traditional birthstone for May.
    • Emeralds are associated with rebirth, spring, and fertility
    • Some people used to believed you could see the future by holding an emerald under your tongue
    • The Spanish conquistadors discovered emerald mines in Colombia and royalty throughout the world looked to South America as the primary source of large emerald crystals
    • Today, emeralds come from Colombia, Brazil, Zambia, Zimbabwe, Pakistan, Afghanistan and Madagascar.

  • GIA Instruments

    GIA Instruments Fact Sheet

    • In 1931, when GIA opened the nation’s first gemological laboratory, there were few precision instruments designed specifically for the science of gemology or jewelry.
    • Most instruments used in the trade at that time were originally meant for use in other fields, such as medicine and dentistry.
    • GIA began designing its own precision-engineered instruments for the growing number of jewelers, scientists and educators who wanted to advance the science of gemology. 
    • In 1934, GIA created the modern jeweler’s loupe.
    • In 1935, GIA designed the handheld polariscope, one of the many instruments that eventually would revolutionize the jewelry trade.
    • In 1938, GIA introduced the first gemological microscope to combine darkfield illumination with binocular magnification. Technology remains the basis for GIA’s best-selling gemological microscopes today.
    • In 1942, GIA introduced the Colorimeter and Diamolite, two groundbreaking instruments that increased accuracy and standardized diamond grading conditions.
    • Today, GIA Instruments offers a wide variety of instruments designed specifically for the gem and jewelry trade, working hand-in-hand with GIA Research, GIA Laboratory, GIA Education and the trade itself.
    • GIA Instruments builds tools that help people buy, grade and appraise gemstones with unmatched accuracy and real-world practicality.

    Visit the Library for more information on emeralds.

  • The RTL Library

    GIA’s RTL Library and Information Center – Fact Sheet

    • The Richard T. Liddicoat Gemological Library and Information Center is the world’s premier resource for information in gem- and jewelry-related fields. Its resources are used by the public, the gem and jewelry industry, and GIA students, staff and alumni.
    • Covering every topic from store operations and business management to treatments and synthetics to the history and science of diamonds, jade, pearls, emeralds and jewelry, the Richard T. Liddicoat Gemological Library and Information Center is recognized as the first point of reference—and the final word—for gem and jewelry information
    • GIA's expert library staff draws upon a growing collection of more than 38,000 volumes, 75,000 photographic images,  1,000 instructional videos and DVDs, 300 international periodicals and the renowned Cartier Rare Book Repository and Archives to provide "ready reference" in the fields of gemology and jewelry.
    • The GIA Library staff answers the questions of scientists, jewelers, gemologists, and students from every corner of the globe. These questions are received by phone, e-mail, correspondence and fax.
    • The public and members of the trade are welcome to visit the Library to use its resources for on-site research.
    • Located on the Gemological Institute of America's Robert Mouawad Campus in Carlsbad, California, the Richard T. Liddicoat Gemological Library and Information Center occupies nearly 8,000 square feet of space, the equivalent of four households of information and facilities.

  • GIA Museum

    GIA Museum Fact Sheet

    • Located at GIA’s headquarters in Carlsbad, California, the GIA Museum (links to Research & Resources/Museum) increases awareness of gems, jewelry, gemology and related technologies through educational exhibits and programs that engage the public and the trade.
    • The Museum actively builds and preserves its collections for education, research and display.
    • The Museum was established in 2001.
    • The Museum has 40,000 items in its collection.
    • The GIA Museum collection consists of gemstones, gem minerals, gem carvings, art objects, jewelry and antique gem equipment. Some notable highlights are:
      • A special collection of contemporary designer jewelry gifted to the Institute by the American Jewelry Design Council (AJDC) in 2004. The AJDC Collection features 29 signature pieces, each representative of the donor’s personal design style.
      • The Brazilian Jewelry Collection, which debuted in 2006 and features traditional and contemporary pieces donated by Brazil’s top designers and manufacturers.
      • The Dr. Edward J. Gubelin collection of over 3,000 gems, acquired in 2005.
      • Pieces from the Academy of Natural Sciences of Philadelphia’s gem and mineral collection, acquired in 2007.
    • Exhibits at the Institute are free and available to the public through scheduled tours.(links to About GIA/Visiting GIA)