At a time before laboratory cut grading, the American round brilliant came to be characterized by a larger table size than was the traditional style in Europe. Eventually a diamond featuring a 60% table and 60% depth (so called 60/60 diamonds) became a commonly referenced standard for a well cut diamond in the dominant US market, despite the fact that Marcel Tolkowsky had demonstrated mathematically the benefits of smaller tables all the way back in 1919.
A 60/60 profile neither guarantees good cut quality nor rules it out. Much more needs to be known about all the parameters of the diamond and whether they all work together. For much more on this topic please see our artice on 60/60 diamonds.
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