Diamonds are graded on a color scale established by the Gemological
Institute of America (GIA). Fancy colors refer to diamonds with hues
like pink, blue, green, yellow, and very rarely red. Fancy colors are
not included in this color scale and are considered extremely rare.
Cut refers to the angles and proportions a skilled craftsman creates in
transforming a rough diamond into a polished diamond. Based on
scientific formulas, a well-cut diamond will internally reflect light
from one mirror-like facet to another and, disperse and reflect it
through the top of the stone. This results in a display of brilliance
and fire. Diamonds that are cut too deep or too shallow lose or leak
light through the side or bottom, resulting in less brilliance, and
ultimately value.
Cutting styles are different than diamond shapes. The simplest and most
common way to explain cutting style is to categorize it into the
following three basic types: Step-cut, Brilliant-cut and Mixed-cut.
A diamond is the hardest known natural substance. It is crystallized
carbon. Diamonds are mined in their rough form and then, cut and
polished to reveal their brilliance.
There are many recognized gemological laboratories that can grade your
diamond for a fee. The most well known is the GIA, Gemological
Institute of America.
When light enters a diamond it reflects off the facets and the angles
cut into the stone. This distribution of light is known as dispersion,
or the display of the spectral colors.
A rectangular or square-shaped cut-cornered diamond. A form of step
cutting, this cut is favored for diamonds and emeralds, as well as many
other stones, when the principle purpose is to enhance color rather
than brilliancy. It is also sometimes used to emphasize the absence of
color in diamonds.
Any flat polished surface of a diamond or gemstone. This style of
cutting gives the stone many small faces at varying angles to one
another. The placement, angle and shape of each facet are carefully
planned and executed to show the stone's inherent beauty, fire, color,
and brilliance to the fullest advantage.
Like the Gypsy setting, this setting has a band that is one continuous
piece that gets thicker at the top. A flat-top setting grows broader at
the top so that a faceted stone can be inserted into the ring at the
broadest part. The stone is held in place by metal chips attached at
the stone's girdle.
When exposed to ultraviolet light, a diamond may exhibit a more
whitish, yellowish or bluish tint, which may imply that the diamond has
a property called fluorescence. The untrained eye can rarely see the
effects of fluorescence. Diamond grading reports often state whether a
diamond has fluorescent properties.
The outer edge of a cut stone, the dividing line between the crown and
the pavilion. Sometimes the girdle is polished and sometimes it is
unpolished. Ideally the width of the girdle should be even and
proportional to the cut of the stone.
These can be considered internal flaws, and can often be seen only by
rotating the diamond very slowly. They can appear and disappear almost
instantaneously. They appear as small lines or planes within the
diamond.
