foundation square (foundashonskwar)

In gem - cutting, one of eight squares formed in bevel planes round the edges of a brilliant, and of which all the angles are subsequently cut away so as to make triangular facets. foundation-stone (foun-da's hon-ston), n. One of the stones of which the foundation of a building is composed; specifically, a corner-stone. My castles are my king's alone, From turret to foundation -stone. Scott , Marmion, vi. 13.