The shape of round brilliant diamonds enchants many couples since it is commonly associated with harmony, wholeness, perfection and unity across many cultures and contexts. This is one of the reasons why round brilliant diamonds dominate roughly three fourths of the market.
With the aid of highly accurate visual computing and laser-cutting technologies, many round diamonds are close to 'perfect round.' But there are still a considerable number of out-of-round (OR) round diamonds in the market: some are the results of technical deviations while others are the outcomes of non-technical considerations such as carat weight preservation.
In an out-of-round diamond, part of the girdle may appear flatter than the rest of the outline. This deviation is more pronounced in large diamonds and those set with prongs (not limited to solitaire prong settings). Plus, it correlates with a couple of other symmetry deviation issues, such as star percentage variation (SPV) and misshapen facet (Fac).
Since the shape of round diamonds can greatly impact their perceived value, out-of-round diamonds are a more economical option when competing with other stones when other specs are equal.
You don't necessarily need to feel disappointed if you get an out-of-round diamond. You can balance out this deviation using some particular settings, such as bezels. The bezel setting uses a thin strip of metal to wrap all edges of the stone moderately. In this manner, the 'imperfection' of the girdle outline is concealed under the strip.
Bezel settings can sometimes visually 'shut off' other symmetry deviations near the girdle, such as non-pointings (Ptg).
Beyond technical aspects, the resulting face-up visual appearance of an out-of-round diamond from the cutting process can impact its final appeal. As long as the brilliance, fire and scintillation of the diamond are at least not below average, these light play effects can somewhat lower people's perception of the OR deviation.