Radiant-Cut

The radiant solves a problem the square and the rectangle both have: sharp corners are the thinnest, most vulnerable part of a stone. Trim them off at an angle and you keep the outline while removing what chips. That is the radiant — a cut-cornered rectangle or square, brilliant-faceted underneath so it crackles rather than flashing in broad planes.

Ratio is where the character sits: near 1.00 it reads square and compact, past 1.30 it stretches and slims a finger. Standard millimeter sizes, and with the corners already handled it takes an ordinary four-prong head in our ring builder.