As the name suggests, shape
is simply the configuration or form of the diamond.
As viewed from the top, the most common shapes are:
Brilliant vs. Step Cut. A "brilliant" cut has triangular
facets which surround the stone and culminate on a flat top. A brilliant cut
can be round, marquise, oval, pear-shaped, heart-shaped, princess (square), or radiant.
A "step" cut diamond is "glassy" in
appearance, since its facets usually span the length or width of the stone. With the exception of the
emerald cut, today's most popular shapes are brilliant cuts or hybrid cuts (as opposed to strict step cuts)
Shape and Cost. In
terms of cost, the round brilliant tops the list, while
the square cuts typically cost about 10% less for a
diamond of the same weight and quality. Note that there
are lots of other shapes not mentioned here, many of
them proprietary and/or patented. Examples include the
Lucida (patented and trademarked by Tiffany & Co.),
the Asscher (patented and trademarked by the Royal Asscher
Diamond Company). Because the manufacture and sale of
diamonds in these shapes are restricted by the respective
patent and/or trademark holders, consumers can usually
expect to pay a premium over the more standard shapes.
There is no "right" or "preferred" shape. Unless
you're purchasing a diamond as an investment (in which case
you should strongly consider a round brilliant), you should
choose the shape which pleases you most.