30Jul

Rosy Blue 4 C's

1. History and general information

The 4 C's of Diamond Quality

Decades ago, the diamond manufacturing, retail and jewellery industry was very disjointed. Many different names, meanings and referrals were used in different places. “It made sense that a certain system had to be developed so that everyone with a link to the business could see, speak and understand the same language,” says Dannie Bellens, diamond expert at Rosy Blue NV. That’s why in the mid twentieth century, the four C’s were created by Robert M. Shipley of the Gemological Institute of America (GIA), as a standard to describe diamonds. These four pointers refer to the attributes that determine a diamond’s quality: colour, clarity, cut and carat weight. The standardisation of determining a diamonds’ worth was an important step, because it enabled universal communications throughout the business.

Today, assessing the 4 C’s remain the universally adopted method of determining the quality of a diamond. In this process, gemologists examine the gemstones under controlled lighting and viewing conditions. All of this takes place in secured, modern labs. And to ensure that the gemstones are screened objectively and consistently, each diamond is assessed by multiple gemologists. After the assessment, it will be determined whether the gemstone is natural or laboratory-grown, and what quality it is. Then the graded diamond will get its own grading report. Thus, since the development of this assessment method, both traders and purchasers know precisely what they’re buying.

2. Colour

Colour: one of the 4 C’s of Diamond Quality

One of the four C’s in determining the quality of a diamond stands for ‘colour’. Diamonds come in a range of hues and different natural colours (such as blue and red) so to be able to grade the colour of a gemstone, the international diamond grading system was created. This system assigns letters, starting at ‘D’ and ending at ‘Z’ in alphabetic order, to certain diamond colours. And when it comes to diamonds, less colour equals a higher grade. So ‘D’ stands for colourless diamonds, and ‘Z’ stands for diamonds with a light yellow or brown colour. Although completely colourless diamonds are very rare.

The colour grade of a diamond is determined by comparing it’s colour to the colour grades on the international GIA (Gemological Institute of America) diamond grading scale. And because both light and background can affect a diamond’s appearance, colour grading is always done in a standardised viewing environment. In the process of colour grading, at least two colour graders submit their independent evaluations. To further ensure a correct colour grading, additional graders may have to enter their individual opinions on the colour of a diamond. Only after sufficient consensus is reached will the colour grade of a diamond be determined.

3. Clarity

Clarity: one of the 4 C’s of Diamond Quality

One of the four C’s determining the quality of a diamond stands for ‘clarity’. To be able to grade the clarity of a gemstone, the GIA’s (Gemological Institute of America) universal clarity scale includes 11 grades. This scale refers to the amount of visible inclusions or blemishes on a diamond and ranges from ‘flawless’ to ‘I3’. At ‘I3’ these inclusions or blemishes are visible to the naked eye, while at grade ‘flawless’ none are visible at even 10 times microscopic magnification. Other than visibility, size, relief, position, nature and the number of inclusions also play important roles in determining a diamond’s clarity. The process of grading its clarity also determines whether or not a gemstone has been subjected to clarity treatments such as fracture filing or laser drilling to improve its grade of clarity.

The grade of clarity is determined under standard viewing conditions at 10 times microscopic magnification. In this process, at least two graders submit their opinion on a diamond’s clarity, symmetry and polish. This ensures a correct and consistent clarity grading.

An important note is that even though some diamonds may be graded as equals when it comes to clarity, it doesn’t necessarily mean that they’re equal in value. Other descriptors come into play when assessing the end value of a diamond, so each descriptor must be taken into consideration when making a comparison between different diamonds.

4. Cut

Cut: one of the 4 C’s of Diamond Quality

One of the four C’s in determining the quality of a diamond stands for ‘cut’. To determine the quality of a cut, a cutter’s skill in cutting the diamond is assessed. In other words, the craftmanship of the cutter is evaluated by grading the diamond’s proportions, symmetry and polish. As such, this is not to be confused with a diamond’s shape or facet arrangement, although both affect the sparkle and brilliance of a diamond directly. So, to quickly summarise: a diamond’s cut refers to the way it returns light and emits sparkle, while a diamond’s shape refers to its silhouette.

To grade the cut of a gemstone, a universal cut scale of five grades was invented by the GIA (Gemological Institute of America). This scale is used to grade round, brilliant cut diamonds and ranges from excellent (0) to poor (10). The cut of a diamond is determined by a highly precise measuring device. This device automatically rotates the gemstone 360 degrees. Because this process is carried out by a machine, hundreds of measurement and facet angles can be captured. Characteristics such as the proportions, culet size, girdle thickness, polish, and symmetry descriptions of a diamond all contribute to its cut grade.

5. Carat weight

Carat weight: one of the 4 C’s of Diamond Quality

One of the four C’s in determining the quality of a diamond stands for ‘carat weight’. To be able to determine the carat weight of a gemstone, an extremely precise and calibrated electronic scale is used. This specific scale captures the exact weight of a diamond to the fifth decimal place. One carat has a weight of 200 milligrams or 1/5 gram, which will be subdivided into 100 points. This means capturing a gemstone’s weight to the fifth decimal place allows us to determine its exact weight to the nearest then-thousandth of a carat. So, although the actual size of a diamond and its carat weight are related, carat refers solely to the diamond’s weight.

The diamond’s proportions, measurements, and facet angles are determined by another optical measuring device. This extremely accurate digital carat scale is used in the process of weighing a diamond. These processes are automated and take place in closed chambers to ensure precise measuring. After the measuring process, the true physical size expressed in millimetres and the weight expressed in carat (ct) is determined.