Oval brilliant cut diamonds buying guide

Oval brilliant cut diamonds seem to be enjoying a renewed sense of popularity this year, so I thought that you might appreciate some helpful insider tips for what to look for when buying an oval shape diamond. Unlike Brian Gavin Signature round, princess, and cushion cut diamonds, which are graded by the American Gem Society Laboratory and which are accompanied by an ASET image that provides you with an indication of how bright the diamonds will be and how evenly light is being distributed among the facets, the majority of oval cut diamonds are graded by the GIA.

What shape of oval diamond appeals to you?

One of the first things you’ll want to decide before buying an oval cut diamond is what shape of oval brilliant cut diamond appeals to your personal sense of balance. Unlike round brilliant cut diamonds, oval shape diamonds are not symmetrical in shape, they can be longer or shorter in length. The oval shape diamond pictured to the left measures 8.88 x 6.01 mm (L x W) and has a length to width ratio of 1.47:1.00 which is within my preferred range of 1.40:1.00 to 1.60:1.00 because it produces what I consider to be a classic oval shape diamond. To determine the length to width ratio of a fancy shape diamond, simply divide the length by the width and compare it to 1.00:1.00 which would be perfectly round. Take notice of the dramatic bow tie effect the diamond above exhibits.

The bowtie effect is the black streak that runs across the middle of this diamond. It is an optical effect created by differences in refraction that occurs at the junction point in the middle of the diamond where the longer facets located on the bottom half of the diamond (the pavilion) which run north to south, meet up with the shorter facets which extend outwards from east to west.

While all oval cut diamonds and pear shape diamonds will exhibit a bowtie effect to some extent, some oval cut diamonds exhibit more of a bowtie effect than others. The diamond pictured above has a rather dramatic and pronounced bowtie effect, however the oval cut diamond pictured to the left does not. This is not due to the proportions of the diamond, the fact is that both of these diamonds have a total depth and table diameter that is quite close to each other. Rather this is due to differences in the facet structure of the diamond, the actual facet pattern polished on to the surface of the diamonds, which are both GIA Excellent cut.

Pay close attention to how light is reflecting in the tips of both the oval cut diamonds pictured above. Notice how light and bright the tips of the oval cut diamond pictured first in the article appear to be, and how dark the tips of the second oval cut diamond pictured in the article happen to be. The fact is that while both of these diamonds have a symmetry grade of GIA Excellent, the fact of the matter is that there are issues with the optical precision that each diamond has been cut to exhibit, neither one is refracting light really well.

Best proportions for oval cut diamonds:

Unfortunately, this is typical of the majority of oval cut diamonds, which are not really cut to the same precision as Brian Gavin Signature diamonds, such as our hearts and arrows round, princess cut, and cushion cut diamonds. But some are cut better than others, and we offer a selection of oval cut diamonds within the virtual inventory of Brian Gavin Diamonds, which is sourced from a handful of diamond cutters who tend to produce better oval cut diamonds.

Those which tend to exhibit the highest volume of light return are those with a total depth between 55 – 60% and a table diameter between 59 – 63% with a crown height between 12 – 15% and a girdle thickness between thin to thick, according to a legacy proportions chart created by appraiser David Atlas, which I find to be helpful when searching for oval cut diamonds.

Since it can be extremely difficult to find oval cut diamonds within this tighter range of proportions, you might consider expanding the range to include a total depth up to 65.4% and a table diameter up to 64% if the first search parameters does not yield any satisfactory options.