How to measure for stone size

[autumngems]

I bought a CS that has 6 sides hexagon, do I measure by the flat sides or at the points to determine size of setting? Also would 4 or 6 prong be best?

 

[Stone-cold11]

Depends on how you mount it?

 

[autumngems]

Round setting

Flat sides would be 6mm, measuring by point to point is 7mm

 

[Stone-cold11]

I mean if you want to mount the stone in a 6 prongs setting, with the flat side in the prongs then measure the dimensions from edge to edgem if points are in the prongs, then point to point.