Ponnuki

Ponnuki, also called a Diamond formation, is the five-stone shape formed when one stone is captured and removed. Four stones of the capturing color remain connected around the empty point where the captured stone stood, creating a compact diamond- or flower-shaped formation.

This shape is strong because it combines substantial influence with tactical stability. The term primarily describes the resulting formation; nuki refers to the act or result of capturing a stone. However, a ponnuki is not automatically the best outcome. Its practical strength depends on the surrounding position: the capture may give the opponent a useful forcing move, or the resulting stones may be inefficient in context.