GEORG SPRENG unique pendant with diamond of approx. 1 ct,

GEORG SPRENG unique pendant with hexagonal fantasy-cut diamond ca. 1 ct, NATURAL YELLOW/I1, 18K yellow gold and platinum, 5.7x5 cm, with NIESSING necklace L: 45 cm, 18K yellow gold, 36 g, 1993, good condition, with maker's sign, designed and handcrafted for DE BEERS competition 'Facets of Fantasy' 1993, model 'Flower Roundelay'.