Diamond Clarity

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Diamond Cut

People often confuse a diamond's cut with its shape. Whereas shape refers to the physical form and contour of the diamond, the quality of its cut dictates overall proportion and how it reacts to light. A diamond's sparkling character and reflective brilliance increases in proportion to the fineness of its cut.

Cutting Process

Using saws, diamonds are cut into round shapes. Other shapes can be cut from the rounded shape such as heart shapes. The shape is not as important as the quality of the cutting that should be done. The diamond will not sparkle and shine well if it is poorly cut. Cutting of each and every facet of the diamond is important for the required geometrical shape, which will allow it to sparkle and shine. The whole diamond can also be cut into a particular shape such as a princess cut or an emerald cut diamond.

After the cutting is done, the diamond is placed in a dop, which is similar to a cup, with another diamond. A diamond is even strong enough to cut out corners of another diamond. After the cutting and shaping takes place, and following the smoothening of its edges in the dop, the diamond is polished on a diamond polishing wheel or a scaif.

Cut Characteristics
The cut of a diamond includes considerations like symmetry, depth, crown and pavilion angles, uniformity of facets, quality of polish and the overall skill of the cutter that sculpted the stone. Most gemologists consider cut to be the most important diamond characteristic. A poor cut will dull the brilliance of a diamond of perfect color and clarity

Cutting a diamond to ideal proportions sometimes requires sacrificing up to half of the crystal's initial weight. Consequently, such diamonds are sold at a relatively higher per-carat price.

Education On Diamond Cut
Brilliant cut:
Brilliant-cut is a specific diamond cutting style developed to maximize a diamond's optical properties. A Brilliant-cut diamond can have several shapes: Round, Princess, Marquise, Radiant, Pear, Oval, Heart and Cushion. A Brilliant-cut diamond that is well-cut, highly polished and well-balanced in proportion will give you that stunning fire, brilliance and sparkle you're looking for.

Education On Diamond Cut
Diameter:
The width of the diamond as measured through the girdle.
Table:
The largest polished facet located on the top of the diamond.
Crown:
The top part of a diamond extending from the table to the girdle.
Girdle:
The edge of the diamond where the crown and pavilion meet.
Pavilion:
The bottom part of a diamond that extends from the girdle down to the culet.
Culet:
The small or pointed facet at the very bottom of a diamond.
Depth:
The height of the diamond as measured from the table to the culet.


Cut is the most difficult characteristic of a diamond to grade because it is based on a combination of aspects. These include crown depth, crown angle, pavilion depth, pavilion angle, the symmetrical arrangement of facets, polish - and more. Since the perfect balance of each is difficult to determine, the variance in the proportions between an Ideal Cut and a Poor Cut can be difficult to discern. Accordingly, the industry developed Diamond Cut Grading Standards to help in determining the quality of a diamond's cut

The cut grade only applies to Round diamonds because they were the focus of the initial research conducted by cut grading laboratories. Though grading laboratories are slowly introducing cut grades for the fancy shapes like the Princess, Emerald, Oval, Radiant, Cushion and others, fancy shape diamonds with a laboratory cut grading remain rare. Each diamond shape has its own set of cut parameters that produce the optimal light performance and beauty for that particular shape.


Cut Grade Description

Excellent/Ideal
Perfectly proportioned and offering the highest grade of polish and symmetry, these stones reflect virtually all light. These diamonds are the most brilliant, rare and finest money can buy.


Very Good

Usually cut to maximize the size of the diamond, a Very Good Cut stone falls a little short of the ideal diamond proportions. A Very Good Cut Diamond reflects most of the light that enters the stone to provide a high level of brilliance.


Good

When a cutter chooses to create the largest possible diamond from a rough crystal, the proportions of the stone are beyond the ideal range. Much of the light that enters the stone is reflected back to deliver a good sparkle. This type of cut grade is an ideal choice for shoppers who want to stay in budget without sacrificing quality or beauty.


Fair and Poor

These stones are cut to maximize carat weight over other considerations. A diamond in this grade will reflect only a small proportion of the light that enters into it.



Other Characteristics

 

Polish

GOOD POLISH RESULTS IN ENHANCING BRILLIANCE                  POOR POLISH RESULTS IN REDUCED BRILLIANCE


Polish refers to the overall smoothness of a diamond's surface. Polish grades indicate how visible the polishing marks (blemishes that are not significant enough to affect the clarity grade of the diamond) are on the facets of the diamond.

Though polish marks are almost always invisible to the unaided eye, they have a slight effect on the diamond's overall brilliance. Examples of blemishes that might be considered polish marks include faint polishing lines and small surface nicks or scratches. These marks are caused by microscopic diamond crystals that are pulled across the facet of the diamond by the polishing wheel during the cutting process.

Diamond polish is graded according to the following scale:
> Ideal Polish lines or marks are extremely difficult to locate under 10x magnification.
> Excellent Polish lines or marks are very difficult to locate under 10x magnification.
> Very Good Polish lines or marks are difficult to locate under 10x magnification.
> Good Polish lines or marks are relatively easy to see under 10x magnification, but remain invisible or extremely difficult to see with the unaided eye.
> Fair Polish lines or marks are obvious under 10x magnification, but remain difficult to see with the unaided eye.
> Poor Polish lines or marks are easy to see without magnification.

Choosing Polish Grade

Consider choosing a diamond with a Good polish grade. While diamonds with higher polish grades are desirable, there are fewer of them. Accordingly, they are generally more expensive than Good rated diamonds despite the fact that they are not noticeably better when viewed with the unaided eye.

Be careful when buying diamonds with polish grades of Fair or Poor. The quality of their polish may limit the brilliance of the diamond.

Symmetry

Symmetry refers to the appropriateness of the diamond's shape and facet arrangement. Brilliance is diminished as a result of symmetry flaws such as variation in shape, alignment and the placement of diamond's facets in relation to one another. Symmetry grades indicate how visible these symmetry flaws are in the diamond.

Major symmetry flaws are often seen in diamonds that are graded as Fair or Poor. These flaws can include severe misalignment of facets, a noticeably off-center table, a noticeably off-center culet, a noticeably 'wavy' girdle, or a table which is noticeably not parallel to the girdle.

Diamond symmetry is graded according to the following scale:
> Ideal Misshapen or misaligned facets are extremely difficult to locate under 10x magnification.
> Excellent Misshapen or misaligned facets are very difficult to locate under 10x magnification.
> Very Good Misshapen or misaligned facets are difficult to locate under 10x magnification.
> Good Misshapen or misaligned facets are relatively easy to see under 10x magnification, though invisible or extremely difficult to see with the unaided eye.
> Fair Misshapen or misaligned facets are obvious under 10x magnification and difficult to see with the unaided eye.
> Poor Misshapen or misaligned facets are easy to see without magnification.

Symmetry Placements


Off-Center Table
The placement of the table (the largest facet on a diamond) should be centered at the top of the stone and needs to be parallel to the girdle. If the table is off-center or not parallel with the girdle this can cause uneven crown angles from one side to the other. In this example we see the unbalanced appearance that occurs from an off-center table.


Off-Center Culet
To check if the culet is centered, look at the diamond in the face-up position. You'll see the lower girdle facets through the table. If the lines formed by them look like a perfect square, the culet is centered. If the cross bends one way or the other, the culet is not centered. In this example we see what an off-centered culet might look like.



Table & Girdle Not Parallel
Here we see another example of what occurs when the table is not parallel with the girdle. As you see, the crown angle is much more steep on one side versus the other. From the top view you may have noticed an off-center table.




Choosing A Symmetry


Consider choosing a diamond with a Good symmetry grade. While diamonds with higher symmetry grades are desirable, there are fewer of them. Accordingly, they are generally more expensive than Good rated diamonds despite the fact that they are not noticeably better when viewed with the unaided eye.


Be careful when buying diamonds with symmetry grades of Fair or Poor, The quality of their symmetry may affect the brilliance of the diamond.

Depth & Table %

Depth% Depth percentage is an expression of how deep a diamond is. It is determined by dividing the height of the diamond (measured from the table to the culet) by its diameter. Each diamond shape has its own range of ideal depth percentages.

Table %
 The table percentage is measured by dividing the width of the diamond table by its diameter. Since depth and table percentage has a major impact on a diamond's brilliance, gemologists consider these important characteristics when evaluating a diamond's cut.





Length/Width Ratio

The length-to-width ratio of a diamond indicates how square or rectangular the diamond is when viewed from the top. This ratio applies to all diamond shapes except Round diamonds. Since length-to-width ratio has a major impact on a diamond's beauty, gemologists consider it an important characteristic when evaluating a diamond's cut.

Princess
If you prefer a square-shaped Princess diamond, choose a length-to-width ratio between 1 and 1.05. For a quality rectangular shaped Princess diamond, look for a length-to-width ratio greater than 1.10.


Marquise
Diamonds with a classic Marquise shape usually have a length-to-width ratio between 1.75 and 2.25.


Emerald
If you prefer an Emerald cut with a square outline, look for an Asscher-cut diamond. For a classical Emerald shape, look for a length-to-width ratio between 1.30 and 1.50.


Radiant
If you prefer a square shaped Radiant diamond, look for a length-to-width ratio between 1 and 1.05. If you prefer a rectangular shape, the length-to-width ratio should be greater than 1.10.

Pear
A classical Pear shaped diamond has a length-to-width ratio between 1.45 and 1.75.


Oval
Classical oval shape diamonds have a length-to-width ratio between 1.33 and 1.66.


Heart
A wider Heart shape will have a length-to-width ratio between 0.85 and 1.00. For a longer, tapered design, try a length-to-width ratio between 1.00 and 1.10.

Asscher
A classical Asscher shape has a length-to-width ratio close to 1.00. If you prefer an Asscher-cut style with a more rectangular outline, look for an Emerald-cut stone.

Cushion
Those seeking a square shaped Cushion diamond should look for length-to-width ratio between 1 and 1.05. For a rectangular shaped Cushion, try a length-to-width ratio between 1.10 and 1.20.

 
     



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