▎ 摘　　要

NOVELTY - The utility model claims a gem grade diamond synthesis device with large cavity, comprising a pyrophyllite composite block with a hollow cavity; two ends of the hollow cavity are symmetrically provided with a conductive steel ring and a conductive metal sheet jointed with the conductive steel ring; between the upper and lower two layers of the conductive metal sheet located at two ends of the hollow cavity is provided with two layers of graphite layer, between the graphite layers of the sheet sequentially is filled with pressure pad, carbon source layer, a catalyst layer, a porous graphene filter layer and a crystal bed; between the two layers of the graphite layer is vertically provided with a through pressure pad, a carbon source layer, a catalyst layer, a porous graphene filter layer and graphite bed of the conductive core column; the inner side of the hollow sequentially is provided with a heat preservation layer from outside to inside, a conductive layer and a pressure transmission layer. The device can reduce the temperature difference between the outer edge of the large cavity and the core, and improve the quality stability of the single crystal.