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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, and these features are called the 4Cs.

Carat Weight:
One carat equals 0.2 grams. Each carat is divided into 100 points for diamonds under a carat, 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 the world's premier gem quality and authenticity evaluations.

Clarity:
The GIA Clarity Scale includes eleven clarity grades ranging from Flawless to I3. Because diamonds form under tremendous heat and pressure conditions, 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 colors and measures the degree of color within the diamond, all measured by comparing the diamond to a set of master stones.

Cut:
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 white light reflecting from a diamond's surface and interior, and fire describes the colored flashes 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.

When exposed to ultraviolet radiation, many diamonds emit a visible light, called fluorescence.

GIA revolutionized the diamond industry in 1955 with its Diamond Grading Report. Based on the 4Cs of diamond value and the International Diamond Grading System™, 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 finishes, clarity, color, and cut grades. In addition, it identifies any known treatments. While several 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 in the traditional diamond grading report but 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 determines 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 significantly impact 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 depend 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.

A minimum of two graders assign 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.

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 brilliant round 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, usually worn daily.

But even a diamond isn't indestructible, and 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.