Diamond

Diamond cut refers to the design and shape in which the diamond has been fashioned. Diamond cut is the most important and difficult parameter among all the 4C’s because the poor cut diamond cannot reflect the maximum amount of light. Many people think that diamond shape and diamond cut is the same thing but diamond cut is more than that. Cut means how precisely a diamond has been made from its rough stone rather than which shape it has been fashioned into. Diamond cut is all about maximizing the reflection of light which overall determines the beauty of the diamond in the form of Brilliance, Fire and Scintillation.


Brilliance:-
Brilliance means the amount of white light reflected by the diamond i.e. the amount of brightness the diamond have. When light hits the surface of the diamond, some light enters the diamond while some is reflected back from the table of the diamond, the light which is reflected back increases the brightness of diamond.

Fire:-
Fire is the different colors that are reflected from the diamond. When the light enters the diamond from the top of the crown i.e. table, it is broken down into different colors inside the diamond that is reflected back from the top of the crown.

Scintillation:-
Scintillation is the sparkling of white and colored flashes when you tilt the diamond from one side to another. Scintillation is composed of pattern and sparkle. A pattern is the size and contrasts of the dark and bright areas which result from internal and external reflection. Sparkle is the movement of light when you tilt the diamond.

The quality of diamond cut depends on the following:-

1. Durability:- Durability means the toughness of diamond which completely depends on the hardness of culet and girdle. So the cutter has to take proper care while making girdle and culet.

2. Polish:- Polish means the condition and quality of the surface of a polished diamond. Polish of the diamond is one of the important parameters while grading the diamond cut. While polishing, cutter has to see whether any polish lines, burn marks, lizard skin, etc. are left into the surface of the diamond.

3. Symmetry:- Symmetry means how accurately the various facets of a diamond are cut. Alignment and intersection of the various facets are considered in order to give Excellent - Poor symmetry grade. Two kinds of symmetry are considered:-

      • Proportion Symmetry:- Proportion symmetry means the alignment of the diamond’s table, culet, girdle and relative angle of the different facets.
      • Facet Symmetry:- Facet symmetry means the placement and exact shape of the facets of the diamond and extra or missing facets.

4. Weight Ratio:- Weight ratio means the ratio between the carat weight and average girdle diameter of the diamond.

   Facets of a Standard Round Brilliant:-


Table:-
Table is the largest facet of the round brilliant diamond and its shape is octagon. It is found on the top of the crown. Through this facet, most of the light is reflected back and enters the diamond. The cut and size of the table affect the brilliance and sparkle of the diamond.

Crown:-
Crown is the top most part of the round brilliant diamond that is just above the girdle. Crown is composed of table, star facet, bezel facet and upper girdle facet. Light enters the diamond through the table and is reflected back.

Star facet:-
Star facets are the triangular facets which extend from the table up to the upper girdle facets. There are in total 8 star facets on the round brilliant diamond. When you see from the top of the crown, they look like points of star, so they are called star facets.

Bezel facets:-
Bezel facets are also known as kite or upper main facets. They extend from the table to the girdle of the diamond. There are in total 8 bezel facets and they look like a 4 sided kite and that is why they are called kite facets.

Upper girdle facets:-
Upper girdle facets are located between the bezel facets and girdle. There are in total 16 upper girdle facets.

Girdle:-
Girdle divides the diamond's crown and pavilion and it is one of the important parts of diamond as it makes the diamond properly mounted on the jewellery.

Pavilion:-
Pavilion is the bottom part of the round brilliant diamond that is just below the girdle. Pavilion is composed of pavilion main facet, lower girdle facet and culet.

Lower girdle facets:-
Lower girdle facets are located between the lower girdle and culet. There are in total 16 lower girdle facets.

Lower girdle facets:-
Pavilion main facets extend from the culet to the lower girdle. They look like an arrow and so they are also termed as arrow facets. There are in total 8 pavilion main facets.

Culet:-
A culet is the small facet at the bottom of the pavilion, which looks like a small round spot. Modern round brilliant diamond does not have culet.

GIA has provided a diamond cut grading system which is used to evaluate the quality of the round brilliant diamond, which are as follows:-
1) Excellent
2) Very good
3) Good
4) Fair
5) Poor



Diamond appearance affects on following proportion:-



Girdle diameter:-
Girdle diameter is the biggest part of the diamond and it is measured in millimetres. It is measured from one edge of the diamond to the opposite edge. Measure the diameter at several places and find the biggest and smallest diameter and find the average of it.

Total depth:-
Total depth is the total height of the diamond from table to culet and it is measured as a percentage of the average girdle diameter.


GIA cut scale depends on following proportions:-

  GIA Symmetry Proportion:-  


Diamond Shape

Diamond shape is the appearance of diamond having different characteristics which determine the quality of diamond. There are many shapes which are very different and have unique characteristics which are as follow:-



Round Brilliant:-


Round brilliant diamond is the most popular and old shaped diamond which is available today. Round brilliant diamond has 57 facets which consist of 32 facets at the crown and 24 facets at the pavilion. Because of its circular shape proportion, it reflects the most fire and light as compared to other shapes. While preparing round shape, more parts of the rough stone has to be removed during cutting stage compared to the any other shape.

Marquise:-


Marquise shaped diamond has the same 57 facets like the round brilliant i.e. 32 facets at the top and 24 facets at the bottom. Marquise shaped diamond can maximize the carat weight as it can utilise the maximum portion of the rough stone as compared to the round brilliant. The length to width ratio for the marquise shaped diamond is 1.75 : 2.25.

Heart:-


Heart shaped diamond has 53 facets but that can be modified as per the requirement. The length to width ratio for the heart shaped diamond is 0.85: 1.

Oval:-


Oval shaped diamond has standard 57 facets like the round brilliant diamond but modification in the main pavilion can be done as per requirement. The oval shaped diamond is just the variation of the round brilliant diamond. The length to width ratio of the oval shaped diamond should be 1.40: 1.60.

Pear:-


Pear shaped diamond is the tear shaped diamond and it is a combination of the round brilliant and marquise shaped diamond. Pear cut diamond has 56 facets in total but can be cut with different numbers of pavilion main. Pear shaped diamond is mostly used in pendants and earring. The length to width ratio of the pear shape diamond is approximately 0.90: 1.10.

Princess:-


Princess shaped diamond is the square shaped diamond with sharp and uncut edges. Princess shaped diamond has good fire and high degree of brilliance. It utilises the most portion of the rough stone, so the overall weight of the diamond is high as compared to round brilliant. The length to width ratio of the princess shaped diamond is 1 : 1.10, so it appears like square to the observer.

Emerald:-


Emerald shaped diamond is the step cut diamond which means it has rows of facets. It has 49 facets in total which comprises of 24 crown facets, 1 table facet and 24 pavilion facets. It shows less fire and brilliance than the round brilliant cut diamond because of the size and shape of the facets. Inclusions and low colour grade can be noticeable easily in emerald shape than any other shapes, so high quality emerald cut is preferred. The length to width ratio of this shape is 1.30: 1.
Radiant:-



Radiant shaped diamond is the combination of square shaped diamond or rectangular shaped diamond. Radiant shaped diamond has 70 facets i.e. 25 on the crown, 8 on the girdle and 37 on the pavilion. Radiant shaped diamond is the oldest shape discovered so it is also called the father of the fancy cut. The length to width ratio of radiant shaped diamond should be 1: 1.05.

Cushion:-



Cushion shaped diamond is found in wide variety of pattern that is known as ‘Cushion Brilliant’ and ‘Modified Cushion Brilliant’. Cushion shaped diamond is less brilliant than the round shaped diamond but can disperse more spectral color from the white light which enters the diamond. The length to width ratio of the cushion cut diamond should be 1.10: 1.20.

Fluorescence
Fluorescence is that characteristic of diamond which makes it to change color when it is subject to ultraviolet (UV) light. Even our white teeth get brighter when it is subjected to UV lights. The same effect on diamond is visible when it is under UV light. Most of the time, when the diamond is subjected to UV light, blue color appears but sometimes it may be yellow.

According to GIA, the fluorescence has very little effect on diamond and an average person cannot make a difference between a diamond with faint fluorescence and a diamond with medium fluorescence. GIA has provided scales in order to determine the amount of fluorescence the diamonds have which are:

1) None
2) Faint
3) Medium
4) Strong
5) Very strong



As the fluorescence glow is usually blue, it makes the diamond of I-M category looks one grade whiter when it has medium to very strong fluorescence, which fetch some extra premium on sell of that diamond. A diamond with very strong fluorescence sometimes looks oily or hazy.

Color
Diamond color is one of the important factors to be considered while grading, as it is noticeable to the naked eye and increases the value of the diamond through its brightness and fire. Many people have misconception that the color of diamonds increases their value but the fact is that the colorless diamonds (white colored diamonds) are more valuable as they are rare and have more transparency which allows the light to be passed through it easily. The most common colors of diamond are yellow and brown which are caused by nitrogen traces, but these colors decrease the value of the diamond. However there is a type of diamond, known as fancy colored diamond, they actually have a color like blue, pink and even yellow which increases the value of the diamond. Colorless diamonds, also called white colored diamonds, are rare and they carry high value because of the brightness, fire and scintillation they have.

GIA (Gemmological Institute of America) has provided a universal standard with wide D-Z range in order to grade (assort) the diamond on the basis of the amount of color it has. The range starts with D, which describes absolutely colourless and ends with Z, which describes light yellow.







Clarity

Clarity describes the amount of internal inclusions and external blemishes present in the diamond. The fewer the inclusions and blemishes present in the diamond, the more valuable and rare the diamond is. Inclusions are the internal flaws present inside the diamond while blemishes are the external flaws present at the surface of the diamond. Diamond clarity depends more on the internal inclusions, as external blemishes can be removed during polish and finishing stage. Internal inclusions distract the amount of light that enters the diamond which reduces the brightness and fire of the diamond.

Diamond clarity is determined by five factors:-
• Size of the inclusions
• Number of the inclusions
• Position of the inclusions
• Nature of the inclusions
• Color of the inclusions

GIA has provided a universal standard for clarity grading which are as follows:-





Carat
Diamonds are measured in carat which is a unit of weight, not size. The word ‘Carat’ is derived from the Arabic word carob, which a type of seeds which were used in earlier days in order to measure the weight of diamonds. One carat equals to 0.20 grams or 200 milligrams. One carat is divided into 100 cent so, for example 0.80 carat equals to 80 cents.

Electronic scale is a measurement device which provides an accurate weight of a diamond as compared to old method of using carob seeds or rice. Most scale can measure hundreds or even thousands of carats of diamond.
Pointers are the specific weight of diamond which are accepted universally in order to make it standardised while making jewellery of the same sized diamonds. A diamond with the pointer has high value as compared to a diamond without pointer. There are two different kinds of pointers, one which is provided by GIA and another is normal pointers.

There is a huge difference in value of a diamond of 0.99 carat and full 1 carat as diamonds with pointers have great value.

Measuring diamonds:- A diamonds proportions and size are measured in millimeters. Millimeter gauge and Sieve are used in order to measure the length and width of diamond.



It is an excellent tool to measure the diamonds. It can measure the total height from table to culet and the total diameter of the diamonds. It measures the dimensions in millimeters. It can measure one diamond at a time.



Millimeter gauge is an important tool to measure large diamonds but to measure and sort the large quantity of small diamonds, sieve set is useful as it can sort large quantity of rough diamonds smaller than 3 mm, at a time. It consists of a holder and sieve plates with different sizes of holes in it. The various sieve sizes available are as follows:-

For example If a sieve plate has 2 mm diameter of holes than a diamond with 2 mm of diameter or less can only pass through it, a diamond with 2.10 mm of diameter cannot pass through it.