The 4 C’s
Established in 1931, GIA (Gemological Institute of America) is the world’s foremost authority on diamonds, colored stones, and pearls. Here the institution breaks down what exactly the 4 C’s are and why they’re important when it comes to your diamond.
Cut quality is the factor that fuels a diamond’s fire, sparkle and brilliance. The allure and beauty of a particular diamond depend more on cut quality than anything else.
The GIA Diamond Cut Grading System for standard round brilliants in the D-to-Z color range is based on the assessment of seven components. The first three — brightness (the total light reflected from a diamond), fire (the dispersion of light into the colors of the spectrum), and scintillation (the pattern of light and dark areas and the flashes of light, or sparkle, when a diamond is moved) — are appearance-based aspects. The remaining four — weight ratio, durability, polish, and symmetry — are related to a diamond’s design and craftsmanship.
The diamond industry as well as the public can use cut along with color, clarity, and carat weight to help them make more informed decisions when assessing and purchasing round brilliant diamonds.
Because diamonds form deep within the earth, under extreme heat and pressure, they often contain unique birthmarks, either internal (inclusions) or external (blemishes). Diamond clarity refers to the absence of these inclusions and blemishes. Diamonds without these birthmarks are rare, and rarity affects a diamond’s value. Using the GIA International Diamond Grading System™, diamonds are assigned a clarity grade that ranges from flawless (FL) to diamonds with obvious inclusions (I3).
Like the color scale, GIA’s clarity grading system developed because jewelers were using terms that were easily misinterpreted, such as “loupe clean,” or “piqué.”
Diamond color is all about what you can’t see. Diamonds are valued by how closely they approach colorlessness – the less color, the higher their value. (The exception to this is fancy color diamonds, such as pinks and blues, which lie outside this color range.) Most diamonds found in jewelry stores run from colorless to near-colorless, with slight hints of yellow or brown.
GIA’s color-grading scale for diamonds is the industry standard. The scale begins with the letter D, representing colorless, and continues with increasing presence of color to the letter Z, or light yellow or brown. Each letter grade has a clearly defined range of color appearance. Diamonds are color-graded by comparing them to stones of known color under controlled lighting and precise viewing conditions.
Before GIA developed the D-Z Color Grading Scale, a variety of other systems were loosely applied. Because the creators of the GIA Color Scale wanted to start fresh, without any association with earlier systems, they chose to start with the letter D—a letter grade normally not associated with top quality.
Diamonds and other gemstones are weighed in metric carats: one carat is equal to 0.2 grams, about the same weight as a paperclip. (Don’t confuse carat with karat, as in “18K gold,” which refers to gold purity.)
Just as a dollar is divided into 100 pennies, a carat is divided into 100 points. For example, a 50-point diamond weighs 0.50 carats. However, two diamonds of equal weight can have very different values depending on the other members of the Four C’s: clarity, color and cut. The majority of diamonds used in fine jewelry weigh one carat or less.
Because even a fraction of a carat can make a considerable difference in cost, precision is crucial. In the diamond industry, weight is often measured to the hundred-thousandths of a carat, and rounded to a hundredth of a carat.
The carat, the standard unit of weight for diamonds and other gemstones, takes its name from the carob seed. Because these small seeds had a fairly uniform weight, early gem traders used them as counterweights in their balance scales. Today, a carat weighs exactly the same in every corner of the world.