The 4C’s: Gemstone Cuts

A poorly executed cut can be the difference between a commercial quality and a museum quality gemstone. All of the 4C’s (carat, cut, color, clarity) are important when choosing a gemstone, but the cut is arguably the most important.

A gemstone cutter formally referred to as a lapidary, has the ability to properly assess rough material and determine its potential as a finished gemstone. Heavily included material and phenomena gems are typically fashioned into cabochons and highly transparent, lightly to moderately included. Stones with excellent color saturation are cut into faceted cuts.

When shopping by cut it is important to know the difference between cut and shape. Frequently customers inaccurately use the two terms interchangeably. Cut describes the faceting style i.e. pavilion (bottom) facets shaped into flat rectangular steps, or triangle (referred to as star facets) and kite shaped facets. The number and orientation of these facets determine the particular cut. The shape is much simpler. It describes the general outline of the gemstone, a trillion shape will have a triangle outline and a round shape, of course, will be round.

Below are the most well-known shapes and cuts that you will come across when shopping for a gemstone.

Round	Round is the standard shape when it comes to symmetry and popularity. However, rounds are one of the most expensive cuts because so much carat weight is lost during the cutting process. It delivers the most brilliance. When cut into Portuguese cut, which has 161-176 facets, compared the 58 facets of a standard brilliant cut and never leaves room for a window. A window is present typically in stones with large flat facets near the bottom point facet of the stone, called a culet. To learn more about Portuguese cuts watch this video.
Oval	Oval is the second standard shape, and it is widely accepted and flattering as a cut for all colored gemstones. In recent years, this shape has grown in popularity for diamond engagement rings.
Heart	Heart-shaped stones are fun and feminine. Most fans of this shape are considered hopeless romantics. With the right positioning and number of facets, they can show breathtaking fire and brilliance.
Cleftless Heart	The cleftless heart is often mistaken for the triangular trillion shape. The easiest way to determine which of the two you are dealing with is to imagine a small snippet is removed where the cleft would normally be positioned for a heart. If it appears as a typical heart shape outline then you are buying a cleftless heart. However if it would make one peculiar heart, then you are more than likely dealing with a trillion shaped stone and depending on the width a pear shape.
Trillion	Trillions are triangle shaped stones, cut with three equal sides or two equal sides. Usually, when all three sides differ in length you have what is considered a free-form shape.
Free-Form	Free-forms aren’t always in a triangular-like shape, but when there is no symmetry present when viewing the gem face-up most classify the shape as a free-form.
Pear	Pear shapes are very similar to cleftless hearts, the rounded sides of the shape are referred to as the shoulders. The width and height can vary, and symmetry is an important factor. Keep in mind that when dealing with diamonds, shoulders that are too high or uneven decrease the value of the stone. More elongated pear shapes are also called teardrops.
Marquise	Marquises are often not a very popular stone. Even one point on a stone is hard to protect from chipping but two points double the chance for damage to occur. However, many people describe those who love this shape as having creative minds and free-spirit personalities.
Emerald	Named after the green beryl gemstone, emerald cuts come only in a square or rectangular shape with the step-cut style facets, which appears exactly as it sounds, a series of rectangular flat facets coming down each side of the stone as well the face-up facets. Some have extra facets added, in which case the stone is labeled a “modified emerald cut.” It is not uncommon for emerald-cut stones to possess a window in the center when viewed face-up.
Elongated Emerald	Some emerald shaped stones have unequal portions, typically where the length of the stone is three times (or more) the width of the stone. These are considered “elongated” emerald cuts.
Cushion	Cushion cuts, or “antique cushions” utilize star and kite facets like the majority of gemstones. This cut is likely to have a window center unless the lapidary adds additional facets towards the culet (bottom point of stone). Many choose not to on rare gemstones due to weight loss.
Princess	The two most commonly confused cuts for many customers are the princess cut and the radiant cut. Princess cut stones will always have pointed corners and radiants will always have cut corners. The numerous bottom facets of a princess are small, centered and gravitating towards the point, creating a pool of never-ending sparkle.
Radiant	Radiant sparkle is comparable to a princess cut, however, you have more options. While princess cuts are only fashioned into squares, radiant’s are available in both rectangular and square shapes. In addition, the cut corner decreases the chances of chipping without adding full corner “V” prongs, which can take away from the overall face-up appearance.
Cabochon	Cabochons are typically used for highly included, opaque stones and phenomena gems for example stones that display asterism, chatoyancy etc. They can have a high dome, low profile dome, or a flat top like many opals. Transparent fine quality material cut into a cabochon, or “cab” for short, are often highly valued because the cut prevents weight loss more than any other cut increasing the per carat price. The numbers of shapes that can be cut into a cabochon are unlimited.
Fancy Cut	Fancy cut/shape gemstones have the typical star and kite facets and an uncommon shape (octagon, trapezoid etc.). Some fancy stones may have both an unusual shape for a gem in addition to a unique facet pattern.
Slice	Slices are typically used for watermelon tourmalines and trapiche emeralds (pictured left) as they are the most effective display of unique colors and patterns within a gemstone or mineral.
Honorable Mentions
Checkerboard Top	Although checkerboard faceting is seen on a wide variety of gem material, the style is most popularly used on opaque aggregate stones like onyx in order to give the stone dimension and sparkle as the light strikes each individual facet.
Laser Cut	Laser cuts can be done to any stone but are typically only used on inexpensive stones with very few inclusions, most often quartz varieties, fluorites, topaz and red garnets.