Carat weight is the measurement used for diamonds.
A metric "carat" is defined as 200 milligrams. Each carat is subdivided into 100 "points". This allows very precise measurements to one hundredth of a decimal place. A jeweler can describe the weight of a diamond less than one carat by its "points" alone. For example, the jeweler may refer to a diamond that weighs 0.25 carat as a "twenty-five point". The weights of diamonds greater than one carat are expressed in carats and decimals. A 1.08 carat stone would be described as “one carat and eight points”.
All other things being equal, the price of diamonds increases with weight as larger diamonds are rarer and more desirable. However, two diamonds of equal carat weight can have very different values (and prices) depending on three other factors of the 4C's of the diamond: color, clarity and size.
While you now know what a carat means, it's also important to remember that a diamond's value is determined using all 4C's, not just carat weight.
Understanding what the color of the diamond means helps in choosing the right diamond. Interestingly, the assessment of the color of a gem-quality diamond is based on the absence of color. A chemically pure and structurally perfect diamond has no hue, like a drop of pure water, and therefore a higher value.
The D-to-Z Color Calibration System measures the degree of color by comparing a stone under controlled lighting and precise viewing conditions against base tones, of a set color value.
Many diamond color distinctions are so subtle that they are invisible to the untrained eye, however, these distinctions make a very big difference in the quality and price of diamonds. Therefore, it is important to obtain the advice of an expert from the GIA to guide you in the best possible way, with full knowledge of the facts.
To understand the purity of diamonds, we must first understand how diamonds are created. Natural diamonds are the result of carbon exposed to tremendous heat and pressure deep within the earth. This process can lead to various internal features called “inclusions” and external features called “imperfections”.
Evaluating the purity of a diamond involves determining the number of impurities, their sizes, their relief, their nature and the position of these characteristics, as well as how these affect the general appearance of the stone.
If you are trying to determine what is the best clarity for a diamond, remember that no diamond is perfectly pure. But the closer it gets to purity, the better its clarity and the higher its price.
The GIA Diamond Clarity Scale includes 6 categories, some of which are divided, for a total of 11 specific grades.
1 - Flawless (FL) No inclusions and no external flaws visible under 10x magnification
2 - Internally Flawless (IF) No inclusion visible under 10x magnification
3 - Very, very small inclusions (VVS1 and VVS2) so light that they are difficult to see for an experienced diamond dealer under 10x magnification
4 - Very small inclusions (VS1 and VS2) Inclusions are observed with difficulty under 10x magnification, and can be qualified as minor
5 - Slight inclusions (SI1 and SI2) Inclusions are easily visible under 10x magnification
6 - Inclusions (I1, I2 and I3) Inclusions are very evident under 10x magnification, which can affect transparency and gloss.
Many inclusions and imperfections are too tiny to be seen by anyone other than a Qualified Diamond Dealer. To the naked eye, a VS1 diamond and an SI2 diamond may look the same, but these diamonds are quite different in terms of overall quality. This is why an expert and accurate assessment of diamond clarity is extremely important. Knowing what diamond clarity really means helps you understand the factors that contribute to diamond quality and price.
Diamonds are renowned for their ability to transmit light and sparkle intensely. We consider the size of a diamond according to its shape (round, heart, oval, marquise, pear…). Precise craftsmanship and finishing is required to shape a stone so that its proportions, symmetry and polish provide the magnificent return of light possible.
Getting the best cut for a diamond is reflected in the beauty and final value of the stone. And of all the 4C´s diamonds, this is the most complex and technically difficult to analyze.
To determine the cut quality of the “standard round” brilliant diamond - the shape that dominates the majority of diamond jewelry - you must calculate the proportions of these facets that influence the visible appearance of the diamond. These proportions help gauge what is the best size for a diamond, by studying how well a diamond interacts with light to create desirable visual effects, such as:
1- Brightness: internal and external white light reflected by a diamond
2- Fire: The diffusion of white light in all the colors of the rainbow
3- Scintillation: the amount of sparkle produced by a diamond and the pattern of light and dark areas caused by reflections in the diamond.
Diamond cut quality also takes into account the design and manufacture of the diamond, including its weight relative to its diameter, thickness, symmetry of the arrangement of the facets, and the quality of the polish on those facets.
The cut quality scale for "standard round" brilliant cut diamonds in the D-to-Z diamond color range contains 5 grades ranging from Excellent to Poor.