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Diamonds Color Stones Pearls

About

Venetia and Stella Vildiridis are gemologists, graduates of GIA (Gemological Institute of America) and would like to share their knowledge so that you get to know precious stones better.

What makes diamonds so special? A scientist will emphasize the conditions at which the stone was formed in the depths of the earth: extreme temperatures (900C–1.300C) and pressure (45-60 Kilobars) present only in certain depths estimated around 140–190 km below the earth’s surface. An economist will underline their rarity and their stock-market value that lasts throughout the passing of time. The consumer will focus on the feelings evoked by the sight of the gemstone as it is being bought or offered to them. The dazzling brilliance, beauty, timelessness and uniqueness of a diamond favor its owner with glamour and prestige. And they will all be right. After all “diamonds are a girl’s best friend” as “diamonds are forever”, indeed! The value of diamonds is determined by a combination of 4 attributes, the famous 4 Cs: Carat weight, Color, Clarity and Cut.

Carat Weight

The weight of diamonds as well as of all gemstones is measured in metric carats – one carat equals 200 milligrams. In other words, a 5 carat diamond weighs barely one gram! When all other attributes are the same, then, the larger – heavier a diamond the more expensive it is. We must note here that the increase of the value of a diamond is progressive and not proportional.

View carat weight diagram

Color

GIA, the world’s foremost gemological institute has established a color grading scale for diamonds from D to Z. The scale begins with the Latin alphabet letter D, representing colorless, and continues with increasing presence of yellowish or brown color to the letter Z. The color distinctions from one grade to the other are so subtle that even a trained gemologist finds it difficult to distinguish. Color differences in comparing and evaluating two individual diamonds are easier to discern when the two stones are at least three letters apart in the scale and that is why smaller sub-units of three letters have been included in the grading system.
There also are the so called “fancy - colored diamonds” that appear in all colors with the exception of purple, which theoretically exists but we have still to find one purple-colored diamond. Colored diamonds are even rarer than white ones with the exception of yellow, brown and black diamonds. For example, we have found only a few red diamonds and one of them, less than 1 carat, was sold for the price of an entire skyscraper in the heart of New-York city!

View color diagram

Clarity

Just like fingerprints are unique to each individual person, diamonds often contain inclusions or blemishes that make its individual one unique. Diamonds with no inclusions are an extreme rarity and this category ranks first in the grading system and is called flawless. There follows the internally flawless category for diamonds that do not present inclusions but some minor blemish on there surface. The VVS (very very slightly included) grade comes third for diamonds with so small inclusions that they are hard to be seen even by a trained grader with the aid of a special microscope as the inclusion is minute and very well-hidden. The VS (very slightly included) diamonds might have more than one inclusions but still difficult to detect and always with the use of a microscope. The SI (slightly included) diamonds contain inclusions that can be easily detected with the microscope and the I (included) category includes diamonds with inclusions detectable even with the naked eye.

View clarity diagram

Cut

Cut is the most important characteristic of a diamond as it gives the gem “life” fueling its sparkle and brilliance. It is the combination of the dimensions of the stone and their proportions, together with symmetry and polish. This affects the clarity, the colour, the brilliance and the overall appearance of a diamond since it is the cut that determines the dispersion of light into the colors of the spectrum - fire, and the flashes of light, or sparkle, when a diamond is moved – scintillation.
There are two modern cut types: the brilliant cut and the step cut. The ideal cut is the round brilliant cut, but there are several other brilliant cut types / shapes such as the princess, ashoka, cushion, heart, oval and marquise cuts, etc. Step cuts include emerald, baguettes, asscher cut diamonds, etc.

View cut diagram

Certificate

A diamond should necessarily be accompanied by a certificate determining its quality and thus, its value. There are institutes issuing such certificates or warranties with GIA (Gemological Institute of America) being the most renowned worldwide. There are also the HRD Diamond High Council (Hoge Raad voor Diamant) and the IGI – International Gemological Institute that issue Diamond Quality Certificates, while we also issue warranties in our shops signed by our trained GIA graduate gemologists.
All certificates are issued after a careful examination of the gemstone under 10x magnification.

View a GIA certificate example