Carat Weight
Carat is the unit of weight for all gemstones. One carat is subdivided into 100 "points".
Therefore a diamond measuring 75 points is 3/4 carat in weight, or 0.75ct. There are five carats in a gram.
The word "carat" comes from the seed of the carob tree pod which is found in tropical climates. These seeds were used until this century to weigh precious gems.
Clarity
A diamond's clarity is determined by the number, nature, position, size and
colour of internal characteristics called "inclusions" and surface features
called "blemishes". These irregularities occured in the liquid magna (volcanic rock)
within which the diamond was created. Diamonds are mostly pure carbon, however,
during crystallization other minerals nearby, or even other bits of carbon forming
more quickly may have become trapped within the cooling mass. These show themselves
as the various characteristics which make up the clarity of a diamond (included crystals,
feathers, clouds etc). Clarity is measured on a scale ranging from pure (flawless) to
heavily included (I-3). The clarity of a diamond is graded by using 10X magnification
under good lighting by an experienced grader. The final clarity grade is usually determined
by how easy the inclusions and blemishes are for the grader to see.
Colour
Ideally, a diamond should have no colour at all, like a drop of spring water. Increasing degrees of body colour are measured on a
scale ranging from no colour at all (D) to deeply coloured (Z). Beyond "Z" is the range where the diamond's colour is vivid and rich,
called "fancy colours". Diamonds of known colour are used as comparison stones for colour grading. Grading is done by comparing the
diamond to be graded against these "master stones" under either artificial or natural north daylight ( in the Northern Hemisphere).
A machine called the "Colorimeter" can be used for colour grading but there is no substitute for the trained human eye.
Cut
Cut, sometimes the forgotten "C", ensures that a given stone has maximum brilliance and sparkle which would not be the case were the
stone cut for weight alone. We use the following scale to grade a stone on it's overall appearance. The proportion page shows angles
and percentages for round brilliant cut diamonds; but angles and percentages are for diamond cutters and graders. Simply put, when looking at
a diamond, if it doesn't catch your eye or if it doesn't flash in the light, it's probably not well cut. Good cutting is what brings fire to the ice.
Heart & Arrow
EX H&A(100%)
VG H&A(80%)
NOT H&A
The best proportionate round diamonds, with perfect angles, will make it the most beautiful diamond, called the “Hearts and Arrows” (H&A).
H&A are even better than the excellent cut diamonds.
H&A cut commands a premium price in the market. We grade H&A diamonds with extra specification and do not include them in the regular cut criteria.
Luster
A diamond is the most desired element in the world. Luster is one of its two most valued attributes, brilliance being the other one.
It is one of the most important parameters of grading diamonds. It describes about the fire,
sparkle and scintillation of the diamond. We grade diamonds depending upon the light reflected from it on the basis of two levels of luster:
BRILLANCE
EXCELLENT
VERY GOOD
GOOD
FAIR
MILKINESS
NONE
VERY LIGHT MILKY
LIGHT MILKY
HEAVY MILKY
Milkiness is an effect that we get looking at the diamonds due to some inclusions like clouds present in the diamond.
These avoid reflection of light from the diamond. Such milky diamonds are further classified depending upon the magnitude of milkiness:
OPEN INCLUSION
We grade diamonds on the basis of five types of inclusions such as,Pin Points, Clouds , Crystal, Feathers.
Pin Point:
It is a very small crystal that looks like a tiny dot while using a 10x loupe. Pin Points are generally white in color but occasionally they can be dark also.
Clouds:
A cloud consists of many tightly grouped pin points. Some clouds look like a light haze, while others are dense and almost impossible to see through the naked eye.
Crystal:
It is a mineral crystal contained in some diamonds. A crystal can be of almost any size, colored or colorless, and can appear alone or in groups.
Feather:
A feather is a general term for any break in the diamond.
NONE
VERY SMALL
SMALL
MEDIUM