There are several stages in the cutting of a gemstone each of which may be carried out by a different expert. As an example, a rough diamond crystal could be fashioned into a brilliant cut. This is the most popular cut for this stone because it maximises the gems natural strong light dispersion. However, because each stone is a different shape, or has imperfections within it, or because retaining the weight is of paramount importance, the cut in its ideal form (the "make") may not be possible. Nevertheless the essential aim is to make the diamond bright and sparkling showing flashes of colour called fire.
To this end the size, number and angles of the facets are mathematically calculated. The rough crystal is swan or cleaved to obtain a
basic, workable piece, then turned on a lathe against another diamond to give it a round shape. The facets are then cut and polished in
stages and the stone is given a final polish before mounting.
- BRILLIANT CUT
- STEP CUT
- MIXED CUT
- FANCY CUT
- OLD EUROPEAN CUT
- EIGHT /SINGLE CUT
- OVAL BRILLIANT CUT
- PEAR BRILLIANT CUT
- HEART BRILLIANT CUT
- MARQUISE CUT
- SQUARE BRILLIANT CUT
- EMERALD CUT
- BAGUETTE CUT
- CABOCHON CUT
- CUSHION CUT
- ROSE CUT
- BRIOLETTE CUT
Invented in the 18th Century this is the
commonest cut used for Diamonds and
is designed to reflect as much light as
possible back up through the top. A brilliant
cut stone has 56 facets, not including the
table and culet. During the 19th Century the
brilliant cut was constantly updated and
developed. In the early part of the Century
most stones were cushion-shaped (square
with rounded edges - known as 'old cut') with
a high crown, small table and large culet.
By the end of the Century the crown
became flatter and the table larger to allow
more light to be reflected through the top
of the stone (known as 'old european cut').
By 1910 most Diamonds were round rather
than cushion-shaped (known as 'English round-
cut brilliant'). The flat bottomed culet grew
smaller and by C1920 it had become a sharp
point (known as 'modern brilliant'). Most 19th
Century stones, on close inspection, have facets
which are not exactly symmetrical. This is
common even in good-quality stones. With the
availability of more advanced technology and
cutting equipment in the 20th Century, facets
The Step-Cut (or trap cut) shows coloured
stones to advantage, having a rectangular
or square table facet and girdle, with parallel
rectangular facets. The corners of the fragile
gems may be removed making octagonal
stones as, for example, in most emeralds.
The mixed-cut stones are usually rounded
in outline with the crowns (above the girdle)
cut as brilliants and the pavilions (below the
girdle) step cut. Sapphires, rubies and the most
transparent coloured stones are cut in this style.
The fancy-cut stones have several possible
outlines such as triangular, kite shaped,
lozenge shaped, pentagonal or hexagonal.
The cut may be used for rare gems or to
make the most of a flawed or irregular
Old European Cut
See Brilliant Cut - an early form of brilliant cut
showing the small table facet. Found mostly in
Eight Cut/Single Cut
The eight cut is a modern version of the brilliant
cut, usually used for small Diamonds of under
0.05cts. It has been used since 1910 and is less
costly than the brilliant cut because it contains
considerably fewer facets, and therefore wastes
less material. Jewellery incorporating eight-cut
Diamonds is usually less valuable than a piece
using brilliants. The eight-cut creates a similar
effect, however, the difference is not visible until
examined through a lens.
Oval Brilliant Cut
See Brilliant Cut - used for many
gemstones including Diamond.
Pear Brilliant Cut
See Brilliant Cut - another commonly used
cut, also known as a 'drop'.
Heart Brilliant Cut
A popular cut for engagement rings and used
for many gemstones. This cut was popular as
far back as the 18th Century and then again in
the Edwardian Period.
Marquise Brilliant Cut
Also called 'navette' or 'boat shaped' this is
a modification of the brilliant cut. The shape
was popular in 18th Century French court
jewellery but fell out of favour until the late
19th Century. It has been in use ever since.
Square Brilliant Cut
See Brilliant Cut - also known as 'princess cut'.
So named as it is commonly used for Emeralds
to show the 'garden' of the stone. This was
developed in the 19th Century but not widely
used until the 20th Century.
for larger coloured stones such as Emeralds
The cabachon cut is when a stone is polished
unfaceted to give it a domed top. This has often
been used for heavily flawed stones that would
not benefit from faceting. This cut is almost
always used for opaque stones such as opals
and turquoises. This cut has been used since
the 19th Century.
This is often used for Sapphires or Rubies and
has a distinctive rounded pavilion.
A very old cut dating from before the
16th Century. Mainly used for Diamonds,
being an economical cut. These stones
contain 24 triangular facets on the top and
a flat base. The Victorians also liked
blood-red pyrope garnets cut in this style.
A variation of the rose cut in extended form.
The proportions are the angles, their measurements and their relationship to one another. The specific parts of the cut diamond
measured are the table percentage of the diameter, the crown angle, the pavilion angle, The total depth percentage of the diameter,
The crown height percentage of diameter, the pavilion depth percentage of diameter, lower girdle facet percentage of pavilion depth,
the star facet percentage of the crown and the girdle thickness.
The finish is the quality of polish and the symmetry of the diamond and all the facets. The optical attributes of a diamond are
Brightness, Fire and Scintillation.
Brightness, also called brilliance is the effect of the internal and external reflection of white light. The proportions of the diamond
play the main role in determining the brightness.
Fire refers to the flashes of color resulting from the white light being dispersed into spectral colors.
Scintillation refers to the areas of light and dark when viewing the top of the diamond.
All these are factored with design and craftsmanship to assign a cut grade of Excellent, Very Good, Good, Fair or Poor using the GIA
Cut-grading System for round brilliant cut diamonds.
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