< BACK TO THE DIAMOND BLOG MAIN PAGE
10
January 2018

4Cs – A Quick Guide to Diamond Basics

Until the mid-20th century, there was no standard approach to assessing the quality of diamonds.

This changed when, in about 1940,  Robert M Shipley, a jeweler who professionalized and revolutionized the jewelry industry in America, helped to devise the 4Cs grading system. The 4Cs system is based on grading of the diamond’s Cut, Color, Clarity and Carat weight. It rapidly gained momentum and became the internationally accepted grading standard of the diamond industry.

Let’s take a closer look at the 4Cs:

Carat

Carat is a weight unit used to measure diamonds and gemstones. It was formally adopted in 1907 at the Fourth General Conference on Weights & Measures in France, and soon spread across the globe as the internationally recognized standard.

Carat weight is a unit of mass equivalent to 0.2 grams. So, a 1 carat diamond is equivalent to 0.2 grams (200 milligrams). Smaller diamonds are often measured in carat points. There are 100 points in every carat. A 10-point diamond weighs one-tenth of a carat, or 0.02 grams. As a general rule, larger diamonds are more expensive than smaller diamonds. However, diamond pricing is affected by all 4Cs, so a smaller diamond of higher clarity and color, or a small superbly cut diamond may be priced higher than a larger, lesser quality diamond.

diamond carat

Cut

In their natural state, mined diamonds are rough and unpolished. Over hundreds of years, diamond cutting has evolved as both a science and art, using precise techniques and cut styles to maximize the beauty and value of the polished diamond.

The most common cut, appreciated for its classic appeal and ideal proportions, is the round brilliant. It features the traditional ‘table’ top, widening to the crown (top half), and then narrowing gradually below to form the pavilion (bottom half), all the way to the point tip, known as the culet.

Diamond cut is graded on a scale ranging from Excellent to Poor. Cut grade is determined by the diamond’s proportions and symmetry, which directly affect the way the diamond returns light to the viewer. For example, a pavilion that is cut too shallow or too deep will not make optimal use of light, reducing the diamond’s brilliance, and will therefore have a lesser grade.

 diamond cut

Color

During the long formation process deep in the earth, the diamond develops a natural hue. In its most perfect and prized form, a diamond is colorless and pure. However, this is rare. Most diamonds develop a tinge, whether slight or more obvious to the eye, as a result of the diamond’s chemical make-up or defects to the structure of the crystal lattice.

Over the past 100 years of diamond trading, diamonds have traditionally been sorted according to Color. The Color grading spectrum ranges from Colorless, which presents as a transparent bright white, through to Dark Yellow, the lowest Color grading.

diamond color

Clarity

However beautiful to the naked eye, most diamonds develop internal flaws and external blemishes during the natural formation process.  Internal flaws, known as inclusions, may occur due to structural imperfections or the presence of crystals from foreign materials, causing a cloudy or milky appearance. External blemishes include cracks, chips, scratches, nicks and ‘naturals’, the term given to flaws on the original rough stone that were not polished by the diamond cutter.

Most inclusions and blemishes are very tiny, not visible to the naked eye.   The Clarity grading has traditionally been determined by magnified viewing of a diamond.  Yet whether internal or external, even tiny inclusions and blemishes can disrupt the travel of light as it enters and exits the diamond, affecting the clarity appearance of the diamond in significant ways.

The Clarity standard, used in the international diamond industry, presents a grading spectrum ranging from 0 Flawless (FL) to 10 Included (I3).  Diamonds at the Flawless end of the spectrum are highly desirable and more expensive.

diamond clarity

With the advent of more accurate and consistent diamond grading technologies and methods, such as light performance, standardized clarity grading, and more, the standard 4Cs diamond report is becoming a thing of the past. The 4Cs are just the beginning of a much broader, more comprehensive story of the diamond. In fact, these added layers of diamond grading, beyond the 4Cs, are the best way to truly see the diamond’s unique character and beauty.

Leave a Reply

Your email address will not be published. Required fields are marked *