A number of factors can affect the
cut and proportion of rubies on the market. The crystalline structure of a ruby dictates
its suitability for specific cutting. The most typical shape is a flat tabular hexagonal
shape, but some ruby crystals can be elongated. The most popular shapes of shaped rubies
are ovals and cushions, with shiny crowns of kite-shaped and triangular facets and
pavilions cut out with concentric rows of facets to suit these crystal shapes. either
rectangular or square.
There are also round and triangular rubies,
emeralds, pears, and marquises available. However, these shapes are uncommon in greater
sizes and higher grades.
Ruby is incredibly expensive in its natural form,
thus cutters try to keep as much weight as possible. They could cut the rubies straight
into shallow stones, even if light escapes through flattened pavilions, but it would
result in an unappealing section of passage in the stone known as a window.
Another aspect that influences cutting is pleochroism, which is the appearance of
distinct colors in different crystal directions. In ruby, the color is typically red to
purplish red in one crystal direction and red orange in the other. Cutters can reduce
the orange-red tint by placing the table's facet perpendicular to the long crystal's
direction. Even yet, because the potential weight loss is too large, it is not always
possible to guide a ruby for a perfect color return.Higher grade rubies on one carat are
extremely rare, although commercial grade rubies are widely accessible in a variety of
sizes. The price per carat of a ruby rises considerably as its size increases.