Alive with fire and brilliance, the oval cut is often considered to be one of the most flattering diamond cuts for an engagement ring. The soft curves and elongated shape give an elegant look to the hand and a high-quality oval cut can offering all the sparkle of a round brilliant while giving a flourish of uniqueness to the ring. It is also a cut which optimises carat weight, meaning the longer shape of the diamond causes it to appear larger than other cuts of the same carat weight.

Variations of oval shaped diamonds adorned hands for hundred of years, however it was in 1957 that renowned diamond cutter Lazare Kaplan created the oval cut that we recognise today. Kaplan was born into a family of jewelers and worked closely with his uncle Abraham Tolkowsky (the inventor of the ideal cut) to create the ultimate oval cut diamond. 

The oval cut may not hold the same level of popularity as the round brilliant but it continues to be the perfect choice for those who seek the brilliance of a round but desire something just a little different to stand out from the crowd.


Certification is absolutely essential when buying any diamond. The GIA and AGS are the only certification bodies who can offer an accurate and internationally respected grade for your diamonds making them your best friend when buying a diamond. However, the GIA do not offer a cut grading for an oval cut diamond. Furthermore, due to the complex nature of this unique cut, it is almost impossible to determine any set parameters regarding cut and proportions. Put simply, there are no ‘magic numbers’ when it comes to an oval cut.

Do not let this put you off. Choosing a diamond is all about what you see and there are other ways to determine the quality of an oval cut without an assigned set of figures.

That said, I have created a rough guideline for the cutting proportions of an oval cut. These can be used in conjunction with other aesthetic aspects (such as the bow-tie effect which we will look at later) to help you build an idea of the best oval cut for you.

Table %53 - 6352 or 64 - 6551 or 66 - 6850 or 69 - 70< 50 or   > 70
Depth %58 - 6256 - 57.9 or 62.1 - 6653 - 55.9 or 66.1 - 7150 - 52.9 or 71.1 - 74< 50 or   > 70
GirdleVery Thin - Slightly ThickVery Thin to ThickVery Thin to Very ThickEx. Thin to Ex. Thick
CuletNoneVery SmallSmallMedium> Medium

You can use this chart as a starting point for evaluating the quality of an oval cut diamond, however remember that there is an exciting element of freedom surrounding this cut. It is much more about what looks the best to you than it is about percentages.

Length to Width Ratio

A length to width ratio will indicate how proportionate a diamond is with the shape it is meant to be. This ratio also helps us to understand how the diamond will really look, for example whether the diamond will be elongated and slim or squat and rounded.

Ratios of 1.30 to 1.50 are the most commonly chosen for an oval cut diamond, however as you can see in this image there is a huge spectrum of ratios, and it is entirely up to you which you select. Be aware that opting for a very slim ratio (anything above 1.75) or anything too rounded (1.20 and below) may mean you lose the soft, flattering proportions of a true oval cut diamond.

James Allen has a large selection of Oval Cut Diamonds as has Blue Nile. If you’re considering a princess cut or round cut diamond however, head to Whiteflash and look at their A CUT ABOVE diamonds. These are in my opinion the best cut diamonds available.

The Bow-Tie Effect

The bow-tie effect describes a dark shadow that casts across the diamond in the shape of a bow tie. A prominent bow-tie shadow will greatly diminish the sparkle and brilliance of an oval cut diamond and emphasises the importance of viewing the diamond in the best possible conditions (i.e. high-res imaging) before buying. This 0.82ct oval cut diamond from James Allen displays by the bow tie effect and shows how an intense shadow can detract from the beauty of the stone. Look for diamonds that do not carry this flaw.



To ensure your oval cut diamond looks colorless in a white setting (such as white gold or platinum) I recommend an H in color. This is the sweet spot between price and quality, and this grade is considered to be ‘near colorless’ by the GIA.

Color is a highly personal part of the diamond aesthetic; some people (though not many) are able to recognise slight hues of yellow in diamonds that appear colorless to others. If this applies to you, look at diamonds with a color grading of G. I would not suggest going higher than this, as the price difference will be sizeable while the difference in appearance will be non-existent.

If you are setting your diamond in a warm setting (such as yellow or rose gold) you may consider diamonds that are an I-J in color. Against the tones of the metal, these gradings can still look colorless.


Typically comprised of 58 facets, the patterning and shape of an oval cut diamond makes it adept at concealing inclusions. This is fantastic news for those on a modest budget, as it means a beautiful, eye-clean oval diamond can be found at an SI2 grading.

Take a look on James Allen and use their diamond view technology to truly analyse the clarity of your stone. With 360 viewing and up to x20 magnification it is a great way to familiarise yourself with the impact that the positioning of an inclusion can have on the beauty of a diamond.

Even those with a little more in their budget to play with can begin their search within the SI2 clarity grade. All that truly matters is the appearance of the diamond, and an SI2 with inclusions concealed around the outer edges of the stone will be just as dazzling as a VVS clarity stone (but will save you thousands of dollars).

The Final Word

As there is less demand for ovals than there are for other diamond cuts (such as round and princess) you can expect to pay less per carat for these unusual stones. There is also less waste from the rough when an oval is cut, which again makes them less costly than their highly popular counterparts. An oval diamond truly delivers on all fronts; a flattering cut with optimized carat weight, a concealer of color and inclusions and above all a brilliance and fire that can stand up to any round brilliant.

A GIA or AGS certified diamond is the perfect choice for those looking to break from the norm with an elegant and sparkling selection that sets them apart from the crowd. Partner with a halo and eternity band setting like this striking Heiress Halo Engagement ring from Blue Nile, or keep it sleek and simple like this white gold Chloe ring by Jeff Cooper for James Allen