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 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.
Every diamond is unique, reflecting the story of its arduous journey from deep inside the earth to a cherished object of adornment. Yet all diamonds share certain features that allow us to compare and evaluate them. These features are called the 4Cs.
CARAT WEIGHT:One carat equals 0.2 grams. For diamonds under a carat, each carat is divided into 100 points, similar to pennies in a dollar. For instance, 0.75ct. = 75 points and 1/2 ct. = 50 points.
GIA's D-to-Z color-grading scale, Flawless-to-I3 clarity-grading scale, and Excellent-to-Poor cut-grading scale are 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.
The GIA Clarity Scale includes eleven clarity grades ranging from Flawless to I3. Because diamonds form under conditions of tremendous heat and pressure, internal inclusions and external blemishes are common and help gemologists identify individual stones. The Clarity Scale also helps separate natural diamonds from synthetics and simulants.
COLOR:The GIA Color Scale extends from D (colorless) to Z (light yellow or brown). Although many people think of diamonds as colorless, most diamonds used in jewelry have subtle tints of yellow or brown. Each letter grade represents a range of color and is a measure of the degree of color within the diamond, all measured by comparing the diamond to a set of master stones.
A polished diamond's proportions affect the performance and interplay of light which, in turn, affects its beauty and desirability. Brightness is the combination of all white light reflecting from both the surface and interior of a diamond. Fire describes the colored flashes that can be seen in a diamond. And scintillation is the sparkle of light you see and the overall pattern of bright and dark areas when you look at a diamond face-up. The design and craftsmanship of a diamond also affect its cut quality, and these factors are considered in determining a diamond's GIA Excellent-to-Poor Cut Grade.
Many diamonds emit a visible light, called fluorescence, when exposed to ultraviolet radiation.
GIA revolutionized the diamond industry in 1955 with its Diamond Grading Report. Based on the 4Cs of diamond value and International Diamond Grading System™, both of which GIA created, the grading report provides a comprehensive analysis of quality and authenticity for diamonds in the D-to-Z color range. It contains information on diamond shape and cutting style, measurements and weight, proportions and finish, along with grades for clarity, color, and cut. In addition, it identifies any known treatments. While a number of laboratories issue similar reports, the GIA Diamond Grading Report has earned a reputation for unrivaled accuracy and integrity when assigning diamond grades.
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.
DIAMOND CARAT WEIGHT MEASUREMENT:To determine carats, the diamond is weighed using an extremely accurate electronic micro-balance that captures the weight to the precise fifth decimal place (the nearest ten-thousandth of a carat). An optical measuring device is used to determine the diamond's proportions, measurements, and facet angles. This data is uploaded into Horizon, GIA's computerized operations and information management system.
GRADING DIAMOND COLOR:Since light source and background can have a significant impact on a diamond's appearance, color is graded in a standardized viewing environment against color masters. A minimum of two color graders enter their independent evaluations into the system and depending on the agreement of these grades, and the weight and quality of the diamond, it may be sent to additional graders who enter their own color opinions. The grade is not determined until there is sufficient consensus.
GRADING DIAMOND CLARITY:Diamond clarity is graded under standard viewing conditions with 10x magnification. The preliminary grader carefully examines the diamond in order to identify clarity/finish characteristics and evidence of any clarity treatments such as fracture filling or laser drilling.
A minimum of two graders assigns their impression of the diamond's clarity, polish, and symmetry. Next, they plot the clarity characteristics on the diagram most representative of the diamond's shape and faceting style, selected from a database of hundreds of digitally stored diagrams. Also during this process, the stone is screened to determine if it is synthetic.
GRADING DIAMOND CUT:GIA provides a cut quality grade for standard round brilliant diamonds that fall into the D-to-Z color range. To develop their Cut Grading System, GIA performed extensive computer modeling of round brilliant diamonds over a 15 year period and conducted more than 70,000 observations on actual stones to validate the research. This system can now predict the cut grade for more than 38.5 million proportion sets.
GIA's Diamond Cut Grading System assesses the diamond's overall face-up appearance to predict the intensity levels of brightness, fire, and scintillation (the diamond's sparkle and interplay with light). The result is a comprehensive Cut Grading System that accurately reflects all the critical cut factors of a round brilliant diamond.
Diamonds are remarkably durable, resistant to scratching except by another diamond, and maintain their brilliant fire extremely well. These qualities make a diamond well-suited to regular wear and are perfect for engagement and wedding rings, which are usually worn every day.
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.
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