Normalizing all three stones to 0.8664 carats ( the heaviest weight at 6.00 mm from the section directly above ) this is the approximate millimeter spread for each stone:

The stone cut with an index of 1 will have a diameter of 6.21 mm.

The 'normally' cut stone with an index of 2 will have a diameter of 6.12 mm.

The stone cut on an index of 3 will have a diameter of 6.00 mm.

Naturally, a larger diameter for any given weight is highly desirable.