Diamond Cut

Diamond Cut describes the shape or visible form of a diamond, the style of faceting, the proportions, and the finish. The way a diamond is cut has an enormous influence over its beauty and durability. Diamonds that are well cut are more expensive than diamonds that are poorly cut.

Shape

The shape of a diamond is the general outline and facet arrangement of the diamond. Round diamonds are the most brilliant and most popular shape, but fancy shaped diamonds are appealing also, and a fashion statement. Some popular fancy shapes are the oval, emerald cut, princess, marquise, and the pear.

Faceting Style

There are three basic styles of faceting:

• Brilliant cut
  was designed for maximum sparkle and uses many triangular and kite-shaped facets.
• Step cut
  focuses on elegance by using fewer facets and more trapezoids and rectangles.
• Mixed cut
  combines both the step cut and the brilliant cut styles for unique beauty.

Frequently, the two concepts of shape and cutting style are often described by one term. For example, an emerald cut is a rectangular shaped diamond with step-like facets and forty-five degree corners.

Proportions

A polished diamond´s beauty or brilliance is a product of its complex relationship with light. Diamonds with good proportions optimize the interaction with light, and have good brilliance, fire, and scintillation. How light strikes the surface of a diamond, how much light enters the diamond, and how it returns to your eye are all affected by the diamond's proportions.

When a diamond is cut to ideal or good proportions, light entering the diamond reflects internally from facet to facet and is reflected back out through the crown or top creating maximum brilliance. If the stone is too shallow or too deep, some light will leak or escape through the bottom part of the diamond, giving the diamond a dull or dark appearance.

Proportions that affect diamond brilliance:

Table Percentage
The table percentage is the width of the table, a diamond's largest facet, divided by the diameter of the diamond. The table percentage is one of the many measurements used to determine how well proportioned a diamond is cut, and consequently how much brilliance it will have.

Total Depth Percentage
The total depth percentage is the depth of a diamond divided by its diameter. The depth percentage is one of the many measurements used to determine how well proportioned a diamond is cut, and how much light will be returned to your eye. Diamonds that are cut too shallow or too deep will be perceived as dark or watery and will lack good brilliance.

Crown Angle
The crown angle is the angle formed where the girdle plane meets the bezel or crown facets. Along with the table size, and depth percentage, the crown angle helps determine the amount of dispersion displayed by the diamond and enhances brilliance.

Symmetry
Symmetry refers to the precision and relationship of a finished diamond's facets. Symmetry describes several factors including how the facet edges align with each other; whether the corresponding facets from opposite sides of the diamond align with each other or not; and whether the facets from the crown or top of the diamond are properly aligned with the corresponding ones on the bottom (pavilion). The polish and symmetry grades are listed in each diamond detail page and within the GIA or AGS diamond laboratory report. GIA grades are excellent (EX), very good (VG), or good (G) Fair (F) and Poor (P). AGS grades for symmetry are ideal (ID), excellent (EX), very good (VG), or good (G).

Polish

Polish is the overall condition of the facet surfaces of a finished diamond. The better polished diamonds will exhibit an adamantine luster or mirror-like finish. GIA grades are excellent (EX), very good (VG), or good (G) Fair (F) and Poor (P). AGS grades for polish and symmetry are ideal (ID), excellent (EX), very good (VG), or good (G).

Ideal Brilliance Diamonds

Ideal Brilliance Round Cut Diamonds

Ideal Brilliance Round Cut Diamonds are the very best round brilliant cut diamonds. Each one has been cut to strict mathematical proportions to create the most beautiful diamond. With 58 exactly placed facets, it produces the ultimate in luster and beauty.

Ideal Standard Round Cut

Ideal Standard Round Cut Diamonds demonstrate subtle variations from the Ideal Brilliance Round Cut Diamond. Although dimensional differences affect a diamond's reflection of light, the Ideal Standard Cut still achieves a harmonious balance between its proportions and the display of brilliance.

Pavilion Depth Percentage

The pavillion depth is expressed as a percentage of the distance from the girdle to the culet in relation to the total depth of the diamond. If it is significantly greater than the ideal, the diamond will have a dark center. If it is significantly less, the stone will look watery and lifeless.

Girdle Thickness

The girdle is the edge or outside diameter of the diamond. A diamond's girdle should be uniform and not too thick or too thin. A girdle that is too thin can chip in the setting process or under normal wear. This extremely thin girdle is a negative durability consideration. A normal girdle should be about 1.8% - 3.9% of the overall diameter. If a girdle is too thick it will add unnecessary weight and cause the diamond to look dark.

The GIA descriptions of girdle thickness are Extremely Thin, Very Thin, Thin, Medium, Slightly Thick, Thick, Very Thick, and Extremely Thick. Ideal Brilliance would not recommend purchasing a diamond with an extremely thin or extremely thick girdle.

Culet Size

The culet is the tiny facet, or lack of a facet, at the bottom of the diamond. The culet should be a small negligible diameter. If the culet is too large, light will leak out of the bottom of the diamond reducing brilliance. If the diamond does not have a culet it will come to a sharp point at the bottom. Diamonds without a culet are reported by GIA as "None" and by AGS as "Pointed."

GIA Cut Scale

GIA provides a cut quality grade for standard round brilliant diamonds that fall in the GIA D-to-Z color range. The Design (weight ratio, durability) and Craftsmanship (polish, symmetry) of a diamond also affect its cut quality, and are considered in determining a diamond's GIA Cut Grade.

GIA Cut Grades:

• Excellent
• Very Good
• Good
• Fair
• Poor

AGS Cut Scale

The AGS Cut Scale for round diamonds has 11 numerical grades ranging from 0 through 10, with 0 being the rarest and most desirable, and 10 the least desirable. Light performance, proportions, and finish are considered when assigning a cut grade.

AGS Cut Grades:

• 0 Ideal
• 1 Excellent
• 2 Very Good
• 3-4 Good
• 5-7 Fair
• 8-10 Poor