Cushion, how diamond dreams are made

The Cushion-shaped diamond has been popular for several centuries. According to some accounts, it was the most popular diamond shape in the 19th century. A classic shape for a diamond, Cushions are squarish diamonds with rounded corners. Its large facets give it a look that resembles the shape of a cushion, hence the source of its name.

Like many other diamond shapes, the Cushion’s history includes gifts to royalty and trade by businessmen in the Venetian court. Until this day, it is the one of the most popular diamond shapes in the market.

The Cushion & Pop Culture

Celebrity engagement rings play an important part in the demand for diamonds. In recent years, Cushion-shaped diamonds received a number of mentions in the media. During the finale of The Bachelor in 2011, Sean Lowe proposed to finalist Catherine Giudici with a 3.15-carat Cushion-shaped diamond. Hip hop singer Kelly Rowland received a 4-carat Cushion-shaped engagement ring, as did Glee star Naya Rivera with a 4.5-carat ring and The Big Bang Theory star Kaley Cuoco with a 2.30-carat ring. The media fanfare around these diamond rings led to a rise in this diamond’s popularity.

The Cushion-shaped diamond is a member of the square diamond shapes, one of three groups of diamond shapes. The other two are Rounds and semi rounds – shapes that are based on the Round brilliant, such as the Pear , Oval , Marquise and Heart. 

There are a number of different ways to polish a Cushion-shaped diamond, though usually it has 64 facets. In addition to the large facets on the top, the table – the surface that faces up – is relatively small. Another characteristic of the Cushion-shaped diamond is its depth. More of its weight rests in the lower part of the diamond, making it appear smaller, as the illustration below shows.

A Comparison of Round, Oval, Pear, Heart, Marquise and Cushion-Shaped Diamonds to Scale

Please note – not real size

Compared to Rounds, the value of Cushion-shaped diamonds is about 29%-58% less, depending on color and clarity. The table below compares the value of one carat and 0.95 carat Cushion-shaped diamonds to 1-carat Round diamonds (1 carat Round = 100%) in all colors and clarities. The 0.95-carat comparison is here to highlight the relatively small difference in size that results in a large difference in value.

Polishing the Cushion

When considering rough diamonds for polishing, a manufacturer is usually faced with a number of alternatives to choose from. First, he has to take into account that with Cushions, an important aspect is its exact proportions and faceting. Because of its small table, Cushion-shaped diamonds don’t reflect light as well as other shapes. Therefore, a Very Good Cut or better is important. 

A polisher would usually want to get the best value out of a rough diamond. Consider the choices a polisher faces in the following two real-life examples. First, a 4.49-carat rough diamond is pictured in the 3D render below. The polisher can polish out of it a Round diamond, which will result in a 1.87-carat, D color, VS1 clarity and Excellent Cut. In this case, yield is 41.5%, meaning 58.5% of the rough diamond's weight will be lost in the polishing process.

^{Image: Sarine}

Alternatively, the manufacturer may polish a much larger Cushion-shaped diamond, as shown in the image below. In this case, a Cushion-shaped diamond will take better advantage of the shape of the rough diamond and will result in a 2.66-carats, D color, VS1 clarity and Excellent Cut polished diamond. In this option, the yield is a high 59.4%.

^{Image: Sarine}

For this rough diamond, the polisher preferred a Cushion-shape to a Round because of the value. Despite the higher value per carat of Rounds compared to Cushions, in this case the difference in size is enough to result in a higher value Cushion-shaped diamond. The value comparison below is based on an analysis of current prices in the market and represents the total value of the diamonds.

Getting a Better Yield

In the next example is a 4.55-carat rough diamond. It can be polished into a 1.40-carat, D/IF Round diamond with an Excellent Cut at a yield of 30.7%, as shown below.

^{Image: Sarine}

Alternatively, the polisher may consider a Cushion-shaped diamond, because of the wide shape of the rough diamond. The polisher can better utilize it to get a higher yield. In this case, a 1.70-carat D/IF, Excellent Cut diamond can be made at a yield of 37.4%, as shown below.

^{Image: Sarine}

As we saw in the article on Pear-shaped diamonds, Heart-shaped diamonds and with the Oval-shaped diamonds, even if the optional Round diamond is smaller than the alternative shape, the Round may still have a higher total value. This is true for all shapes, including the Cushion. In this case, even though the Round diamond is smaller, it has a higher value than the alternative Cushion, as the following table shows.

The reason the yield is noted in all these polishing options is because from a financial standpoint, it makes sense to try to get the best return out of the cost of the rough diamond. Given the two different possible outcomes, it is worth comparing the value of different options, and seeing which is more economically beneficial to manufacture.

Necessary Proportions

When polishing a diamond, proportions are important for a number of reasons, including aesthetics. A well-proportioned diamond looks much better than one that is not. Another reason is light return. To get the best light return, light must enter through the top of the diamond, bounce inside of it and then reflect out through the top. The more light that is reflected, the more the diamond shines.

To achieve this, the facets must face each other at the right angles. Below is a list of Cushion-shaped proportions by Cut standard:

As stated in previous articles, the intention of this review is to highlight a number of issues relating to diamonds, their value and how to understand the varying characteristics of diamonds that may seem identical but differ enough to affect their value.

In addition, we presented a table that showed the difference in value between the various diamond shapes. This table is part of the Mercury Crystal Clear™ system. It is important to keep it in mind when considering diamonds as part of a wealth preservation belief or even as a gift.

The views expressed here are solely those of the author in his private capacity. No one should act upon any opinion or information in this website without consulting a professional qualified adviser.