Gemstone Cuts

The most usual method of fashioning a gem is to cut the surface into a number of flat faces, known as facets. This gives the stone its final shape or 'cut'.
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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.

Different Gemstone Cuts

Brilliant Cut Diamond

Brilliant 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
became symmetrical.


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.

Anatomy of A Diamond


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.

Antique Diamond Rings is part of the Antique Jewellery Group where a vast array of rare and distinctive pieces can be found at www.antiquejewellerygroup.com