Diamond with the same weight can have different visible size depending on their shape. This visual size is described by spread characteristic. Positive spread means that diamond looks larger than Tolkowsky round with same weight, negative means opposite.
Consider Apparent size for 1 ct Marquise
Round with Same Face up Area as Marquise has weight 1.29ct
Absolute Apparent size (Spread) shows how much heavier or lighter will be Round with same Face up area as Marquise.
Round with same Face up area will be 0.29 ct heavier than current 1.0 ct Marquise
Absolute Apparent size value depends on the current diamond weight
Relative Apparent size shows weight ratio between current Diamond and Round with Same Face up area.
Round with same Face up area will be 22% heavier than current Marquise.
Relative Apparent size value does not depend on diamond weight. Thus allow comparison between diamonds with different Weight
Consider Apparent size for this 1 ct Cushion
Round with Same Face up Area as Cushion has weight 0.78ct