Natural Diamond Warrantly
Evaluation of diamonds on the international system (GIA)
Since the mid-20th century system of the Gemological Institute of America (GIA) has offered the market the first comprehensive system of grading diamonds as earlier each laboratory, creating a system, change only the terminology and notation, leaving structure unchanged "4C» - Carat (weight), Color (Colour ), Clarity (purity), Cut (Cut).
Let's look at diamond grading system based on GIA
GIA - the International Classification of colors
For the designated color diamonds used letters of the alphabet starting with the letter "D" "E" "F" "G" "H" "I". Thus, the criterion for inclusion of a diamond to a specific color is, the study of stone down on a special pad folded sheet of paper (the boat) under standard homologous lamp giving white "northern" light. Brilliant color "D" - against the backdrop of a colorless boats, with a slight bluish tinge. Moving below in alphabetical order, we find the first stone in the presence of a grayish hue, and then a yellowish hue, which in each of the next group of colors increases.
GIA - the International Classification of frequency
The classification is based on the purity of diamonds GIA on the principle - how difficult or easy the expert to detect defects in the stone and on its surface, using standard homologous 10x-th lens.
The scale starts with graduation FLAWLESS (FL) is the diamonds that have no defects were inside the stone or on the surface, that in addition to magnifying glass microscope is controlled, it is the perfect stones are usually unique, specially ogre auction stones that are not commonly found in the mass markets.
Graduation INTERNALLY FLAWLESS (IF) - Diamonds are intrinsically clean in 10x-th increase, but with small defects on the surface.Graduation VERY VERY SLIGHTLY INCLUDED (VVS) - Diamonds with very, very small defects, and are divided into two subgroups - VVS 1 and VVS 2. The expert takes some time to find these stones in the minor defects that can be seen only from the pavilion.
Graduation VERY SLIGHTLY INCLUDED (VS) - it rocks with very small defects, experts are already visible on the front side of the stone. At the same time, there is a division into sub-VS1 and VS2. Graduation SLIGHTLY INCLUDED (SI) - Diamonds that are immediately obvious to an expert internal defects. In this subgroup of less defective than SI1 SI2.
Last graduation INCLUDED (I) - Diamonds have numerous visible even without a magnifying glass defects in various parts of the stone, depending on the group subdivided by I1-I2-I3.
The quality of the cut
Cut Grade in the early 21st century, gemological Institute of
America - GAI proposed new qualification cut quality, based on the ratio of linear and angular parameters faceted diamond. A distinctive feature of the cut of the diamond is a diamond that is able to transmit the color and shine brightly in different shades. The quality of the cut determines the degree of refraction and the ability to transmit the light refracted it faces. In this cutter from requiring precise artistic and technical work in the stone processing, strict adherence to the proportions of symmetry and polish that would achieve the best effect of the returning light, which is only possible in a diamond. The quality of the cut towers as follows:
Excellent, Very Good, Good, Fair, Poor.
Fancy Color Diamonds - Diamonds fancy color
Apart from the usual all white - koloris (see angd), in our time, the market offers a color - Fancy Color diamonds of different colors and shades. Nature has created diamonds virtually all colors of the rainbow, while some are common, and some are unique.
Causes of different colors.
Let's look at the causes of different colors. The appearance of blue and blue color in diamonds due to boron atoms in the structure. The presence of green caused by the natural radioactivity of rocks which was a diamond, which is why the green color of most of the surface and only rarely painted stone completely.
Yellow color - caused by nitrogen atoms in the diamond structure. Widespread brown and rare and unique pink and red color, due to the plastic deformation of the diamond structure. The orange color is caused by an admixture of hydrogen. Black diamonds due to the large number of small inclusions of sulphides and graphite.
The most expensive and unique colored diamonds are blue, green and red with no shades. Next in value are blue, pink, yellow, green, orange. This is followed by diamonds, colorless, vyvshego color "D". Less valuable - yellow diamonds. List of precious stones do not close the "dirty" color greenish-yellow, brown color ("Champagne and Cognac") and - black diamonds.
The Gemological Institute of America (GIA) has created for colored diamonds classification is based on the color system of Mansel and the ratio of saturation and tone diamond. Formally colored diamonds begin after the color "Z" in the classification for white diamonds - that is true for yellow, but the stones of unique colors - blue, pink, stand out in a special color groups starting from a pale color intensity.
There are the following gradation of color diamonds. Faint> Very Light> Light> Fancy Light> Fancy> Fancy Intense> Fancy Vivid> Fancy Deep> Fancy Dark. Most coveted diamonds are graded with color as the Fancy Vivid and Fancy Deep.
Because the current technology allow you to attach any color diamonds different methods of refining, of particular importance for colored diamonds gets a certificate of homologous known laboratories such as GAI, AGS, ARDI GEM TESTING CENTR, and EGL, Gubelin, AGA, HRD, AGC, SSEF, GRS etc.