What you need to know about diamond shapes and ratios
Learning about diamond shapes and ratios is one of the best places to start when it comes to designing that dream ring so we’ve put together this handy guide. Let’s get started.
What is diamond ratio?
Every diamond is totally unique, from its clarity, colour and importantly, its cut. Each diamond is cut differently and the diamond ratio refers to its proportions: length to width. For every cut, the ideal ratio is different and it is this ratio that will ensure the diamond is in perfect proportion, sparkles in the way it should and reflects and refracts the light to give it that WOW factor.
However, it’s important to note that although these ratios are important, for all of the diamond cuts except the Round Brilliant, the grading organizations around the world from the GIA to the EGL, don’t give a ‘cut grade’ to a diamond. The reason for this is that although this length to width ratio is a good guide, these organisations acknowledge that a ‘fancy cut’ diamond’s shape and beauty are in the eye of the beholder.
As trained diamond graders here at Princess Diamonds, we will look at each diamond and recommend it on its overall beauty.
The most popular cut in the world is the round. If you are looking for a diamond that truly sparkles, this is the one as it is cut to reflect light off its many facets. Most round diamonds are ‘brilliant cut’ and so they have up to 58 facets. This cut is often a little more expensive due to its popularity and the fact that when cut, much of the rough diamond is lost but it is also one of the most adaptable cuts in terms of balancing the other Cs – clarity and colour. The ratio to look for here is 1.00-1.01.
If you are not looking for a round shaped diamond, the princess is a wonderful option. Like the round, it is cut to sparkle and reflect light so that it will catch the eye. It can be square or rectangular in shape and you should look for a ratio of 1-1.05 (more square) or 1.10 if you would prefer a more rectangular shape. The price of a princess cut usually offers better value than the round but like the round, it is a great option for working into almost any design. If you would like to include other smaller stones in your design, a princess works well.
This shape originates from the technique used to cut emeralds. It is quite unlike the round or princess cut in that its look is created by step cuts on all sides of its pavilion (the pavilion is the part of the diamond below the girdle or top section of the diamond). It has a large open table so that it doesn’t sparkle like a brilliant cut but rather it’s the step cuts which catch the light. It’s one of the most elegant cuts but also due to the open facets, this cut is less forgiving when it comes to imperfections and colour. For a classic emerald cut, you should look for a ratio of 1.50.
If you love the sound of the emerald cut but you are looking for more of a square shaped diamond, then the Asscher is what you are after. Due to its shape and therefore the smaller ‘table’ it will also be more sparkly than a classic shaped emerald cut. But as with the emerald cut, the clarity of the diamond can really be highlighted so make sure you ask the right questions and consider the clarity scale before making your final decision. In terms of ratio, look for 1.0-1.05. This cut was first created in 1902 and was popular in the 1920s but thankfully it is now enjoying a revival.
If a big diamond is what you are after, the marquise cut is a good choice as the shape can give the impression of a much larger diamond. The cut produces long and slender diamonds. Depending on how narrow you would like your marquise diamond, a classic marquise has a ratio of between 1.75 to 2.15. This cut, like the round and the princess, is brilliant cut so you’ll also get that magical sparkle. And if you are looking to add smaller stones on either side, this cut works well. Symmetry is so important with this shape so that’s something to watch out for when making your final selection.
As with a marquise, the oval cut is also super popular with those who are after a brilliant cut diamond with all its beautiful facets waiting to reflect and refract light. The oval is a classic cut which has the added benefit of making the ring finger look that little bit more slender. If you are after a ‘rounder’ or ‘fatter’ oval, look for a ratio of 1.25 and for a more elongated oval, go for a diamond around the 1.75 mark.
The radiant cut is perfect for those after a square or rectangular shape but with the twinkle of a brilliant cut. It has trimmed corners and is often paired with smaller stones on either side. For a square radiant cut, a ratio of 1 to 1.05 will work well and for a slightly more rectangular look, a 1.10. The close relatives of this cut are the princess or the cushion and the benefits of this cut over the asscher or the emerald is that it is brilliant cut and therefore any imperfections are more difficult to see.
The pear cut looks very much like a teardrop. It has similar qualities to the marquise in that it is brilliant cut and will help give the impression of longer fingers. With this cut you are looking at a ratio of between 1.45 and 1.75 – with 1.40 being for a more plump teardrop shape and 1.75 being a more long and slender cut. The point of the pear drop should be worn so that it points away from the fingertips. Symmetry is also very important with this cut as if the point is slightly off, the ring will feel lopsided.
Symmetry for a heart shaped diamond is very important as you will want both sides of the heart to look the same. This cut requires a larger diamond to give the stone its heart shape – if the diamond is not big enough the heart may not be as obvious as you would like. A traditional heart shape has a ratio of approximately 1.00 but you can slide up and down depending on how narrow a heart you are looking for. This cut is also brilliant cut so not only does it symbolise LOVE at first sight, it will also shine like a star.
This is one of the most classic diamond shapes – it has been used for hundreds of years – so if a vintage feel is what you are after, this is a wonderful cut to consider. Expect rounded corners but larger facets than say a round or princess cut so clarity is important here. For a square cushion-cut diamond, look for a ratio of 1. And for more of a rectangular shape, go for something from 1.15-1.30.
All of the diamonds we use here at Princess Diamonds are ethically sourced and adhere to the highest standards of responsibility – we only work with suppliers that observe the Kimberly Process Certification Scheme (KPCS). We also only sell Certified Diamonds from the leading international diamond grading organisations; these include the Gemological Institute of America (GIA), European Gemological Laboratory (EGL), and Hoge Raad voor Diamant of Belgium (HRD).
We would love to work with you to design your dream ring. Get in touch and let’s start this magical journey.
Until then, take care of yourselves,
Colleen and Jackie