Radiant engagement rings

Radiant cut diamond cut quality

Finding a diamond with a great ‘Cut’ is the most important factor in ensuring that your stone sparkles as brightly as possible. The GIA issues a ‘cut’ grade for round brilliant stones, which makes finding a high quality stone easy, but there is no such grade for radiant cut diamonds unfortunately. However, there are some key things to keep in mind when choosing a radiant cut diamond:

Radiant diamond length / width ratio

One thing to think about is whether you would prefer a square or a rectangular shaped stone, and this is where the length / width ratio comes into play. A perfect square stone will have a length / width ratio of 1:1 ie. both sides are the exact same length.  A ratio of 1.05 will still look like a square once it’s mounted in a ring, but if you go over this then the stone will start to look more rectangular.

For rectangular radiant cuts, a ratio of 1.2 will start to look slightly rectangular, while 1.5 will mean that it is twice as long along one edge as the other, so the stone will look very rectangular.

So far, so straightforward. Something to know though is that in longer radiant cuts there is a possibility that the bow tie effect will show. How much this affects the stone is very difficult to tell from static images, so if you’re considering a rectangular radiant cut then I would recommend going with James Allen, who offer 360 degree views of each stone so you can ensure that the bow tie effect is minimised.

Radiant Diamond Table Percentage

The ‘table’ of a diamond is the large, flat area on the top of the stone.

The size of the table in relation to the rest of the stone is important because it’s where the majority of light enters the stone. This needs to be carefully balanced with the other proportions to ensure that the correct amount of light enters to allow for maximum sparkle. Contrary to what you might think, a larger table is not always better.

If possible, aim for a table % in the ‘excellent’ range in the table below:

Excellent	Very good	Good
64% – 74%	62% – 76%	60% – 78%

Radiant Diamond Depth Percentage

Depth percentage is the ratio of the depth to the width of the stone.

This is an important factor because if the stone is too tall it will let light leak out the bottom of the stone, and if it’s too shallow it will reflect light back at the wrong angle – both meaning that there is less light returned to your eyes, reducing the amount the stone appears to sparkle.

Excellent	Very good	Good
66% – 75%	64% – 76.5%	62% – 78%

Varying from these percentages is likely to mean a higher proportion of light is lost through the sides and the bottom of the diamond and it will appear less brilliant. The best way to find a stone that fits within the recommendations is is to enter them into the ‘advanced’ options on online jewelers search tools so that you only see stone that fit within the desirable specs.

Radiant diamond color

The sparkle that is the result of the brilliant cut facets of the radiant cut make it a very forgiving cut. It means that you can go lower on the color grade than you can on other, less sparkly shapes. If you’re looking for a white diamond, it’s safe to go all the way down to H on the colour grade without any yellow tones being noticeable at all.

Of course, you can go higher than this, but as the difference between diamond colour grades is so slight, the difference in actual appearance between an H color diamond and an E color diamond will be very slight, if it is visible at all once they are both set in ring settings.

If you choose a color grade lower than H, you are more likely to be able to see ‘warmer’ tones. This is not necessarily a bad thing, but your stone won’t look quite as white as the higher color grades.

Radiant diamond clarity

Clarity is the least important of the 4Cs in terms of what a diamond looks like, but it’s often the C that guys get most obsessed about getting a high grade on. Jewelers love to show the difference between clarity grades when you look at diamonds in jewelry stores, but actually clarity makes very little difference to how impressive a diamond actually is.

With a radiant cut engagement ring, you can safely go down to SI1 if you can inspect the stone and verify that it is eye-clean. Some SI2 stones may even look eye-clean as the excellent sparkle of the radiant cut will disguise the flaws. The two best retailers that offer high quality images of each of their stones to allow you to inspect Slightly Included stones are:

• Blue Nile
• James Allen

With other retailers where you can’t inspect the individual stones, it’s a better bet to play it safe with a VS2 clarity stone.

You can of course go higher than these grades, but you’ll be paying for the stone to be ‘mind clean’ rather than ‘eye clean’, rather than any actual improvement in appearance.

Radiant cut diamond carat weight

Carat weight is something that people often get overly hung-up on. They want to choose a stone with a certain carat weight, even if it means that they end up making sacrifices on other, more important attributes of the ring.

The relationship between a diamond’s carat weight and its visible size isn’t always a direct one. When we judge a diamond’s size, we look at it from the top – known as the ‘face up’ position in the jewelry trade. However, much of the weight of a diamond is actually carried on the bottom half of the stone, where it can’t be seen.

The images below show the difference in size for radiant cut diamonds at a range of carat weights:

Hopefully you can see that increasing the carat weight doesn’t necessarily translate into a much visibly larger diamond. Changing the size from 0.8 carat to 1 carat is an increase in width of just over 0.4mm – less than 10%. However, the difference in price will be much more significant – almost a 60% increase.

The priority that you place on diamond carat weight and how bit you want to go is totally up to you. However, my recommendation is that you definitely don’t make it the most important attribute when choosing your engagement ring. Get the setting you love, find a diamond with a great cut that is going to sparkle brilliantly, make sure that it is eye-clean and has a good color and then see what carat weight you can fit into your budget.

A well-rounded diamond with excellent sparkle will much much more impressive than a big stone with obvious flaws.

Radiant diamond certification

The fifth C, and a very important one too. When looking at any diamond, you need to ensure that any diamond that you’re looking at is a ‘cert stone’, which means that it has been assessed, graded and coded with a laser by an independent lab.

Each certificate has a unique report number and detailed information about the stone, covering the four Cs, the height, depth and other info. As well as providing assurance that the stone that you’re buying is the quality that you are paying for, a certificate also proves what you’re buying is not a substitute.

The lab to trust and to look for certification from is the non-profit Gemological Institute of America (GIA). It’s the most internationally recognised and generally seen as the most impartial of all of the gem labs.

The reason that the GIA is so well respected is because most others labs are part of trade bodies that contain jewelry retailers, or are ‘for profit’. While the GIA is very consistent with its gradings, the others have a reputation for being overly generous. What the GIA say is merely a diamond with a ‘good’ cut, maybe be graded ‘excellent’ by another lab, with an excellently large price to match.

Diamond certificates are what makes buying online safe and the best way to get a fantastic diamond at the lowest price. Knowing that each diamond you’re considering has been measured and graded by independent experts allows you to make an informed decision. You can take your time to consider the differences between diamonds and make sure you choose what experts have graded as the best stone, meaning that you get your perfect engagement ring at the best possible price.