The Diamond Destined for Radiance

Unlike the diamond shapes described here previously, the Radiant-shaped diamond does not have a history dating back centuries. It’s also unique in that it can be either a square or a rectangular shape. Either way, the Radiant is a great alternative for someone who wants a diamond – but with a different shape.

Radiants are newcomers to the diamond scene. They were developed in the 1970s when the Emerald-shaped diamond lost some of its popularity in the American market. Master diamond cutter Henry Grossbard, a legendary figure in the modern diamond industry, set out to create an alternative that would stand out for its brilliance. In 1977, after months of experimentation, he introduced the new creation and called it Radiant. 

One of the unique properties of the Radiant is that it can either be constructed to de-emphasize color, as needed for white diamonds, or to emphasize color, as with fancy color diamonds. 

One classic example of this trait was a famous gift – the engagement ring Ben Affleck gave Jennifer Lopez, set with a 6.1-carat pink Radiant-shaped diamond. The diamond sparked a strong trend for pink diamonds, and brought fancy color diamonds to the public’s attention. 

Like the Cushion and Emerald-shaped diamonds discussed here over the past couple of weeks, the Radiant is a member of the square shape group of diamonds, 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. 

The Radiant has 60 facets or more; and unlike the straight rectangular facets found on Emeralds, many of the facets on the Radiant are triangular. These many facets are what give this diamond shape the great sparkle and brilliance it is known for. On its grading reports, The GIA calls this shape “cut corner rectangular modified brilliant” and “cut corner square modified brilliant.”

A Comparison of Diamond Shapes to Scale 

^{Left to right: Round, Oval, Pear, Heart, Marquise, Cushion, Emerald and Radiant-shaped diamonds (not real size)}

Compared to Rounds, the value of Radiant-shaped diamonds is about 34%-61% less, depending on color and clarity. The table below compares the value of one carat and 0.95 carat Radiant-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 Radiant

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 the color of the diamond, and whether he wants to enhance it (for fancy color diamonds) or suppress it (for white diamonds). 

One of the strengths of the Radiant shape is its ability to “hide” inclusions, like with Cushion-shaped diamonds. If a rough diamond has a centrally located inclusion, it may be an advantage to polish it into a Radiant over other square shapes, such as the Emerald – especially if the rough diamond has a longish shape. 

When the Radiant Is Right

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 4.85-carat rough diamond is pictured in the side view 3D render below. The polisher can polish out of it a Round diamond, which will result in a 1.63-carat, D color and IF clarity. In this case, yield is 33.6%, meaning 66.4% of the rough diamond's weight will be lost in the polishing process.

Image: Sarine

Alternatively, the manufacturer may polish a larger Radiant-shaped diamond, as shown in the top-view image below. In this case, a Radiant-shaped diamond will take better advantage of the long shape of the rough diamond and will result in a 2.13-carat, D color, IF clarity polished diamond. In this option, the yield is 43.9%.

Image: Sarine

For this rough diamond, the polisher preferred a Radiant shape to a Round because of the value. Despite the higher value per carat of Rounds compared to Radiants, in this case the difference in size is enough to result in a higher value Radiant-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.

In the next example is a 7.62-carat rough diamond. It can be polished into a 3.01-carat, D/IF Round diamond with an Excellent Cut at a yield of 39.5%, as shown below.

 ^{Image: OGI}

Alternatively, the polisher may consider a Radiant-shaped diamond, because of the shape of the rough diamond. The polisher can better utilize it to get a higher yield. In this case, a 4.74-carat D/IF, Excellent Cut diamond can be made at a yield of 62.2%, as shown below from a different angle.

Image: OGI

As we saw in the article on Emerald-shaped diamonds or Heart-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 Radiant-shaped diamonds. In this case, even though the Round diamond is 36.5% lighter in weight, it has a higher total value than the alternative Radiant, as the following table shows.

The reason the yield is noted in all these polishing options is that 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 Radiant-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. None of the information made available here shall constitute in any manner an offer or invitation or promotion to buy or to sell diamonds.  No one should act upon any opinion or information in this website (including with respect to diamonds values) without consulting a professional qualified adviser.