Generally the best looking diamonds have table sizes in the range of 55% to 60% (measured as a percentage of the diameter of the diamond). The size of the table is more important in larger diamonds, say over 1/2 ct.
Variations in table sizes are less critical than crown and pavilion angles. Diamond cutters tend to cut larger table sizes than we would prefer because cutting larger tables conserves diamond weight.
Larger table diamonds have a better "spread" and can be more brilliant, i.e. they return the most light, but have less fire and scintillation than diamonds with smaller tables. This is because the ability of a diamond to break light into rainbow colours (fire or dispersion) is enhanced by light entering or leaving a diamond at an acute angle. The same principle applies to cut crystal wine glasses and chandeliers. You can probably visualize the Pink Floyd "Dark Side of the Moon" CD cover. Technically, dispersion is maximized as light approaches the critical angle between the diamond to air interface. The resultant burst of color emerges close to parallel to the surface of the diamond. So if you look from the front of a diamond you are more likely to observe fire from a crown facet. The smaller the table the bigger the crown facets.
Large tables produce less scintillation because there is less interplay between the crown and pavilion facets. Scintillation is hard to define, it is the black – white – black flashing you observe as you roll a diamond (or move the light source). If a diamond had no crown facets at all it would appear very brilliant but dull and lifeless.
You can see on the images here that the smaller table diamonds appear to have more facets than the larger table images. If a diamond had no crown facets it would appear boring.
Table sizes over 60% are more affordable and because there is less crown height, they have a larger spread or diameter. You get a bigger looking rock for less cash. We suggest an upper limit of 63%. You will see that Ideal-Scope images of larger table diamonds often look a little paler just inside the table; but what appears to be 50% pink intensity will actually return 75% or more light.
As table sizes get larger, beware of the fish-eye effect.