Oval Cut Diamond Guide

All about the sensational South African oval diamond.

Oval diamonds have a similar brilliance to round diamonds, but their style is more contemporary and unusual. Seen on the ring fingers of a number of contemporary celebrities, these eye-catching diamonds have become increasingly popular as a stylish and striking choice for engagement rings.

Apart from the flawlessly fashionable appeal of an oval diamond, there are a number of practical reasons for choosing this diamond shape.

  • Oval diamonds set into a ring can elongate the appearance of a woman’s fingers, resulting in a graceful, feminine, and elegant look.
  • It is basically an elongated brilliant cut diamond, so you lose very little of the radiance and fire when compared to a brilliant cut round diamond.
  • Although it is technically a fancy shape, the oval diamond has a stunning and striking simplicity, with soft lines and no sharp areas to chip easily or to catch on clothing.
  • An oval diamond makes an engagement ring perfect for matching with a wedding ring.
  • With an oval diamond the surface area of the stone is greater compared to a round diamond of the same weight. This makes the diamond seem bigger, so you get more bang for your buck or dazzle for your wherewithal. Speak to our experienced sales team at Cape Diamonds for the best price for an oval diamond.

The trending oval diamond has a long history of popularity and associations with royalty and fame. The stunning “Wittlesbach Blue” was given as a dowry for Empress and Queen Margaret Teresa of Spain when she married into the House of Hapsburg in the 17th century. The massive 105 carats “Kol-i-Noor” diamond was acquired by Queen Victoria in the 19th century and now forms part of the Crown Jewels. And the spectacular “Pink Star”, which originated from Botswana, was sold in 2017 for a record auction price of $1.194 million per carat.

GIA grading:  The GIA certificate for a brilliant cut round diamond presents the reader with a predictable quality of diamond, however the GIA certificate for an oval diamond may not give an exact idea of what the diamond will actually look like. This is because, according to GIA grading, there is no “ideal” cut for an oval diamond. You will therefore not only have to scrutinize the GIA certificate, you will also have to visually examine an oval diamond, with the assistance of our experienced team at Cape Diamonds. The GIA certificate for an oval diamond from another jeweller may seem to offer a better stone at a better price, but you will not know what you are getting until you have seen the stone and assessed it with your own eyes. Cape Diamonds purchases well-proportioned oval diamonds.

Perfect proportions: When looking for the best oval diamond, you will need to examine proportions and cut. Seen from above, the diamond should be symmetrical, with each half horizontally and vertically mirroring the other half.

The length to width ratio is also important, with the popular demand being for ovals with a longer shape. The GIA recommends oval diamonds that have 1.3:1 to 1.4:1 ratio, up to 1.7:1 ideal ratio, though the latter are more difficult to find. We find oval diamonds of around 1.45:1 ratio the most desirable and the rounder oval diamonds with ratio of 1.3:1 less popular. Getting oval diamonds with a ratio of 1.2:1 is not the best idea, as they do not have the elegance of the longer stones.

The girdle of an oval diamond should not be too thin or thick. Extremely thin girdles may predispose the stone to cracking or chipping, even though diamonds are among the hardest and most resilient materials found on earth! Girdles that are too thick create an unsightly effect.

Facets: The perfect oval cut diamond follows the cut of a brilliant cut diamond, with 58 facets. The culet is the base facet, which is optional, but should not be too large. If the diamond has no culet, it only has 57 facets. Usually, eight four-cornered bezel facets appear on the crown of the diamond and 16 star facets along with the table facet. The pavilion of the oval diamond has variations. Some pavilions have 4 and 6 lower half facets while others have 8.

At Cape Diamonds, we recommend 8 lower half facets in the same position as a round brilliant cut diamond. The points of the lower half facets in the pavilion of stone should point to the shoulders of the diamond to minimize a bow tie effect and create maximum sparkle (see diagram below).

The Shoulders of an oval diamond are the parts between the belly of the diamond and the head or end of the diamond, when viewed from above. Flat shoulders result in the oval diamond looking too pointy at the head and end, while enlarged, fat shoulders have an ungraceful effect. Speak to an experienced jeweller or salesperson at Cape Diamonds to discuss a perfect proportion for the shoulders of an oval diamond.

Beware the bowtie! This dreaded effect can be seen as a noticeably dark shape resembling a man’s bowtie, across the belly of the diamond. Because of their shape, ovals, marquise and pear-shaped diamonds are prone to this defect. A heavy bowtie effect occurs in a poorly cut diamond, and is actually the result of your own reflection darkening the stone. It therefore tends to look worse up close. Some oval diamonds may have slight bowties that do not significantly affect their radiance and scintillation, and may even add to their unique appeal. However, you should definitely avoid buying an oval diamond where the bowtie effect causes large dark areas. Trust your eyes when you examine an oval diamond in order to bypass the risk of buying a diamond with an obvious bowtie. At Cape Diamonds, we do not stock flawed diamonds with overt bowtie effects, but you may come across these stones elsewhere. Bowties are often a result of the diamond pavilion being cut too deep, similar to a “nail head round diamond”.

Colour and clarity: Like other brilliant diamonds, ovals come in a range of GIA colour and clarity gradings. Our experts at Cape Diamonds recommend oval diamonds in the range D-I for colour, and si2 and above for clarity. Oval diamonds can carry a little more colour in the head part of the stone and will appear more colourless at the belly of the stone, because the colour is reflected into the tighter curve of the girdle.


Setting and design: Oval diamonds look especially striking in solitaire and halo settings. Fashionable band design variations can include double bands and split bands. Due to its length, an oval diamond can make an engagement ring the consummate partner of a matching wedding band, where the two rings complete each other and blend perfectly into the overall design.