Gems 101: Understanding Different Gemstone Cuts and Shapes

When Prince Harry and Meghan Markle announced their engagement, her engagement ring had top billing. The reports in the media described Ms. Markle's beautiful ring as a cushion-cut diamond bracketed by oval diamonds. When gemstones are described, the cut and the shape are often muddled together in this way.

However, cut and shape are two different, although interrelated, aspects of a gemstone. If you'd like to know your marquise from your cabochon, read on for our guide to gemstone cuts and shapes. 

GEMSTONES

Most gemstones are mined. In their natural state, they are usually found as crystals embedded in rough, dull rocks. In recent years, some gemstones have also been successfully grown in labs. Certain types of materials that are usually considered alongside gemstones, such as amber, pearls, and coral, have other natural origins.

It's the art of the gem-cutter, or lapidary, which results in the transformation of this raw, rough material into beautiful sparkling jewels. Archaeological records show that, as early as 3000 B.C., gem-cutters were already cutting and shaping stones for both useful and aesthetic purposes. 

PRECIOUS AND SEMI-PRECIOUS STONES

Different gemstones are more highly-prized than others, depending on their rarity, purity, and cultural value. Diamonds, rubies, sapphires, and emeralds are generally considered to be the most precious of all gemstones. Other types of gemstone, such as agate, aquamarine, onyx, topaz, and so on, are considered semi-precious. 

TUMBLING AND POLISHING

The simplest way of preparing gemstones is to tumble them. Sea-glass, which is glass that has been naturally tumbled and polished by the ocean, is a good example of how this process takes place. To deliberately create this effect, the rough gemstones are placed in a machine that tumbles them around in grit and water for a few weeks until their edges and surfaces are smooth and polished.

Types of stones that are often sold tumbled and polished include varieties of chalcedony, such as agate; types of quartz, such as amethyst and aventurine; mineral gemstones, such as beryls and garnets; rocks, such as obsidian and granite; and fossilized materials, such as turritella and mookaite. Tumbled stones have a natural beauty all their own and are very popular in jewelry-making and other crafts. 

CUTTING FOR BRILLIANCE AND SPARKLE

Gemstone cuts are how their sparkle is determined. Stones which are tumbled and polished don't sparkle. To create sparkle, a lapidary geometrically cuts multiple flat planes, known as facets, into the surface of a stone. These planes then refract the light, creating sparkle.

A skillful gem-cutter will choose a cut that best showcases the unique characteristics of the rough stone, and the accuracy and quality of the cut will determine the beauty and brilliance of the final gem. Cutting may reduce the size of the original stone by as much as half, but its market value may increase significantly, depending on the amount of brilliance and sparkle revealed by the gem-cutter.

In addition to being a gemstone, diamond is the hardest naturally occurring material. Therefore, gem-cutters typically use a diamond to cut other gems, including the diamond itself. Silicon carbide, a manmade compound, is also used to cut colored gemstones.

Common techniques used by gem-cutters include tumbling, sawing, grinding, sanding, lapping, and polishing. Lapping is the signature technique that gem-cutters use. It's a process similar to sanding that creates the flat facets that give cut gems their brilliance. 

GEMSTONE CUTS

Cabochon Cut

The name of cabochon stones is based on an old Norman French word "caboche" that means head. A cabochon-cut gemstone is not really a cut at all, as cabochons have no facets but are tumbled and polished until they reach a smooth, rounded finish and a gleaming shine. Cabochons are then trimmed to fit into their setting.

Cabochon gemstones have been created since ancient times. Opals and moonstones are often cabbed rather than cut to showcase their color and play of light. Opaque gems such as turquoise, malachite, onyx, and agate are often cabbed as well.

The Romans thought faceted gems were rather vulgar, and they much-preferred cabochon gems and carved gems such as cameos and intaglios.

Step Cut

A step cut is created by adding facets in horizontal layers like a set of steps. Step cuts are intended to showcase the color and clarity of a stone rather than increasing its brilliance.

Brilliant Cut

A brilliant cut is a complex, technically demanding cut that places multiple facets at regular angles to create maximum sparkle. There are a large number of variations in brilliant cuts, depending on the shape and size of the rough stone and the intended effect. 

Divine Cut

A divine cut gem is a recently developed variation of the brilliant cut, designed to increase brilliance and light fraction further. In a divine cut, the flat top of the gem is smaller than in most brilliant cut gems, and the arrangement of the facets creates a shape more similar to a parachute than the more familiar trapezoid shape of the standard brilliant cut. 

Ceylon Cut

A Ceylon cut is a mixed cut in which the sides of the stone are cut into steps ascending to a brilliant cut center.

Rose Cut

The rose cut was developed in 1520 and was often used for garnets. A rose cut has a round, cabochon base and a faceted top with a regular pattern of triangular facets. 

Barion Cut

A barion cut combines both step cuts and brilliant cuts in the gemstone. Barion cuts can look very different, depending on whether they are applied to square-, rectangular-, triangular-, or round-shaped gemstones. The distinctive arrangement of the facets in a barion cut gem creates a cross-shaped pattern at the center of the stone. 

Checkerboard Cut

In a checkerboard cut, the facets are all square, to deliver a checkerboard look. This cut is often paired with cushion-shaped and translucent gemstones like tourmalated quartz, as these types of shapes and stones best showcase the intricacy of the cut.   

Eight Cut

An eight cut is a simpler version of a brilliant cut, with only eight facets around the crown of the gem. 

Old Mine Cut

An old mine cut is one of several older cutting styles, including the old European cut and the Mogul cut that preceded the brilliant cut. The aim was to achieve maximum sparkle, but technical limitations meant the stones were taller and the facets were larger than in the current brilliant cuts. Old mine cuts and other older cuts are still sometimes used to create a vintage look. 

GEMSTONE SHAPES

The shape of a gemstone is its outline, as viewed from above, and it’s the shape that often determines the overall style and impact of the finished piece of jewelry. There are several shapes and cut combinations that appear together so often they have been given their own names. 

Round

Round-shaped gemstones are classic and enduringly popular. Round gemstones are usually paired with a brilliant, rose, or cabochon cut. Round, brilliant cut, 58 facet diamond solitaire rings are the most traditional and popular choice for engagement rings, as the combination of shape and cut maximizes brilliance and sparkle.    

Oval

The majority of most rough gemstones are loosely spherical, making the oval the most common shape for colored gemstones. Gem-cutters often prefer an oval shape because they need to balance aesthetic and commercial considerations, and an oval retains a larger amount of the carat weight of the gem than other shapes. Oval shapes lend themselves to cabochon cuts or may be faceted with a modified brilliant cut.

Oval-cut diamonds are not quite as popular or brilliant as round diamonds for engagement rings, but can be a smart choice, as a 56-facet oval gemstone set into a ring works well to visually lengthen and draw attention to elegant hands. When Prince William and Kate Middleton got engaged, she wore the famous oval sapphire engagement ring that once belonged to Princess Diana. 

Marquise

A marquise shape is a pointed oval and tends to be matched with a modified brilliant cut. Another name for the marquise shape is "navette." The pointed ends, and the importance of matching the facets on both sides exactly, make this shape technically demanding to cut and also rather fragile. Therefore, you might find that gems cut into this shape are relatively more expensive than similar weight stones in other shapes.

However, the marquise shape will maximize the visible size of a diamond compared to its carat weight, delivering the look of a much more expensive stone. Like an oval shape, the marquise shape will highlight beautiful hands and fingers and create a long, elegant look. 

Pear

Pear or teardrop shapes feature one rounded and one pointed end. Partnered with a brilliant cut, this shape usually has between 56 and 58 facets. Pear-shaped gems are often used in pendants and earrings, as the elegant shape draws the eye downward.   

Briolette

A briolette-shaped gemstone is a variation on a pear-shape and is usually considered the most difficult shape to cut. The key difference from the pear-shape is that a briolette is faceted on all sides. The briolette shape originated in India in the 12th century and was most popular during the 17th and 18th centuries. Today, it is relatively uncommon and tends to be used in vintage style pieces, especially necklaces and drop earrings. 

Heart

Heart-shaped gems are a modified pear-shape with a division at the top to create the popular sentimental and romantic shape. A brilliant cut is the most common pairing with a heart-shaped gem, and the finished stone usually incorporates 59 facets. The complexity of the faceting requires skillful cutting. 

Square and Rectangle

There are several named types of square and rectangular-shaped gemstones that combine a particular cut with a square or rectangular shape.

• Square –  Princess

A gemstone described as "princess-cut" is usually square with a brilliant cut and pointed corners. You'll often find diamond engagement rings in this shape and cut combination. A princess-cut gem usually has up to 78 facets, and the combination of shape and faceting means this style of gemstone shows its color in the corners of the cut as well as the center. You might find the pointed corners on this style can make it less practical for everyday wear, as they may snag on fabrics, particularly if the gem is placed in a raised setting.

• Rectangle –  Emerald

Am emerald-shaped stone is usually rectangular with angled corners. The top of the stone is flat, and the edges feature a step cut. This shape and cut combination usually looks a little like a window or a mirror and tends to have a subtle gleam that showcases the clarity of the gem rather than an intense sparkle.

• Square –  Asscher

Asscher gemstones are named after a Dutch diamond cutter, Joseph Asscher, who invented and patented this variation of the emerald shape in 1902. An Asscher gemstone has a much smaller flat top than an emerald shaped gemstone, creating an almost octagonal appearance that evokes the Art-Deco styles of the early twentieth century.

In 2001, a new version of the Asscher shape was created by the Asscher family, increasing the number of facets from 58 to 74 and widening the corners. Since then, Asscher engagement rings have become popular with celebrities, and Jessica Alba, Reese Witherspoon, and Gwyneth Paltrow have all been seen showing off an Asscher-style ring. 

• Square or rectangle –  Cushion

Cushion or pillow shapes are variants of square and rectangle shapes with rounded edges and corners. This shape features larger facets, which showcase the clarity of the gem, and it is often used with large and expensive colored stones, making it very popular with celebrities.

• Rectangle –  Baguette

Baguette-shaped gems are long, narrow rectangles similar to thin emerald shapes featuring step cuts around the sides. Baguettes are sometimes tapered so they are thinner at one end than the other. The style was first introduced during the 1920s during the Art Deco and Art Nouveau periods. The cut was an instant hit because of its clean geometric lines, which were very much in fashion.

Baguettes are only rarely used alone as a centerpiece jewel. Instead, you'll usually find them in a supporting role, bracketing a larger central gem or lined up together, contributing to an overall effect.   

Radiant

The radiant is a hybrid shape that offers the square lines of an emerald with the sparkling brilliance of a round gem. 62 to 70 facets are created by trimming and angling the corners of a basic emerald shape to create a beautifully complex blend of shape and cut. 

Trillion

A three-sided, triangular gemstone is known as a trillion or trilliant. Usually matched with a modified brilliant cut style using 31 to 43 facets, this unusual shape can feature either pointed or rounded corners and either straight or curved sides. Trilliants are usually used in modern jewelry designs and offer very sharp brilliance.