A Guide to Square or Rectangular Cut Diamonds

When choosing an engagement ring, one of the first things most people consider is the center stone. It’s often the main attraction, so it certainly warrants some serious thought.

While a round diamond is what most people imagine when they picture a traditional engagement ring, there are many other fancy shapes available for you to consider. There are pear shapes, marquise, trillion, and oval. There are also many that fall into the “square or rectangular” category, but they do have many differences between them which can give your ring a distinct look. Let’s take a look at all the “square or rectangular” shaped diamond options to help you decide if one may be right for your engagement ring–and if so, which one?

Square and rectangular cut gemstones can sparkle beautifully depending upon the quality of the cut, which enhances the brilliance of the stone. Let’s specifically take a look at asscher, princess, radiant, cushion, and emerald cut diamonds in a little greater detail.

Asscher Cut Diamonds

Shape and Characteristics: The Asscher cut is a unique square shape with cut corners. It has 58 large step cut facets, similar to the emerald cut, which allows light to reflect off each facet and have great brilliance.

History: The Asscher cut was developed in 1902 by the Asscher Brothers of Holland and became popular during the Art Deco period. It was further developed into the Royal Asscher cut in 2001, which has 74 facets, creating more brilliance.

Setting and Use: Asscher cut diamonds are very popular for engagement rings, especially mountings that have a vintage feel. They look beautiful on their own in a solitaire, and even more so when flanked by a pair of matching Asscher cut diamonds in a 3-stone ring. You also often see Asscher diamonds in a halo setting, but typically with round melee (Asscher melee is difficult to find and very expensive), which makes the center stone appear larger.

Princess Cut

Shape and Characteristics: The princess cut is the most popular of the “square or rectangular” category and you’ll often see them in engagement rings advertisements or in jewelry store cases on display. After the round brilliant cut, it is the most popular diamond shape. The princess cut is a modern square shape with typically 57 or 76 facets and has intense sparkle. The facets in a princess cut are similar to the facets in a round brilliant cut diamond, which increases the light return, making these stones sparkle more than others in the same category.

History: The princess cut was developed in the 1960s and has remained very popular for modern engagement rings.

Setting and Use: Princess cut diamonds are versatile and can be set in a solitaire, halo, three-stone ring, etc. It’s important to know that princess cut diamonds need to be set with v-shaped prongs. Because these diamonds have sharp corners, they can easily chip and need to be protected with the metal on the v-tip prong to avoid damage.

Radiant Cut

Shape and Characteristics: The radiant cut is a combination of the emerald cut and the round brilliant cut. It belongs in this category because it can be either square or rectangular and always has trimmed corners. With 70 facets, the radiant cut diamond has great brilliance.

History: The radiant cut was developed in the 1970s by Henry Grossbard, who wanted to combine the round brilliant cut and emerald cut diamond.

Setting and Use: Radiant cut diamonds are often set in solitaires, three-stone rings, and halo settings. Because the radiant cut has trimmed corners, it is less prone to chipping, which allows it to be set with regular prongs instead of v-tip.

Cushion Cut

Shape and Characteristics: The cushion cut has gained popularity within the past decade or so and can also have either a square or rectangular shape, but with rounded corners and curved sides. It is sometimes referred to as “pillow cut.” The cushion cut usually has 58 facets, but it can vary depending upon the exact shape and the stone cutter.

History: The cushion cut dates back to the 19th century, before the round brilliant cut became popular. It somehow manages to have both a vintage and modern appeal.

Setting and Use: Cushion cut diamonds are most often seen in vintage style engagement rings and halo settings. The rounded corners make them durable, and they can be set using a variety of setting styles instead of the v-tip prong.

Emerald Cut

Shape and Characteristics: The emerald cut is the only true rectangular shape in this category, with long, straight facets and cut corners. Emerald cuts are not known for their sparkle necessarily, and due to the way the 58 facets are cut, they offer depth that other shaped diamonds do not.

History: The emerald cut was developed during the Art Deco period and became popular in the 1920s.

Setting and Use: Because emerald cut diamonds are such statement stones, they are often set in solitaires with prongs.

Don't Forget The 4Cs

Of course when choosing any diamond, it’s necessary to consider the 4Cs, which we can briefly touch on now. The  4Cs are cut, color, clarity, and carat weight. The cut grade–determined by the diamond’s proportions–can vary based on the grading lab. Terms like "ideal" or "excellent" may be used, but they essentially indicate the same level of quality. While carat weight measures the diamond’s size, let’s focus on color and clarity.

The color grade evaluates how much color is present in a diamond. The GIA’s scale runs from D (completely colorless) to Z (light yellow or brown). Diamonds graded D - F are considered colorless, while lower grades show more traces of color, usually yellow. However, diamonds with some color can still be stunning, especially when set in yellow or rose gold, which can enhance the stone’s hue. Fancy color diamonds, like canary yellow or blue, are rarer and are graded on a separate scale, commanding higher prices due to their rarity.

Clarity measures how flawless a diamond appears under magnification. The clarity scale ranges from Flawless (no visible inclusions) to Included (inclusions visible to the naked eye). Higher clarity grades typically come with higher price tags. Grading reports often include a map showing where inclusions are located on the diamond, allowing you to see how unique your diamond is.

Inclusions vary in type and impact. Pinpoints are tiny crystals that usually don’t affect appearance. Feathers are small fractures that may or may not be visible and can affect both the look and durability of the stone. Clouds are clusters of pinpoints that can give the diamond a hazy appearance, depending on their size. Crystals are small mineral spots inside the diamond that can influence appearance based on their size and location. Needles are long, thin crystals that are generally invisible unless particularly large.

Selecting an engagement ring involves more than just picking a beautiful stone. There are many aspects to consider and when there are a variety of stones that look somewhat similar, understanding what makes them unique can assist in the shopping process. All of the shapes in the “square or rectangular” category vary in brilliance, facets, and light return. Some of them have specific needs for setting consideration, and they all have their own aesthetic.

As you consider the asscher, princess, radiant, cushion, and emerald cut diamonds, remember to consider the 4Cs as well and you’re sure to end up with a beautiful engagement ring that you’ll be happy to wear for the rest of time.