An ice making assembly includes a conductive ice mold, an insulator ice mold, and an external insulator jacket. The conductive ice mold extends along a vertical direction between a top conductive mold end and a bottom conductive mold end. The conductive ice mold defines a mold cavity having a vertical opening at the top conductive mold end. The insulator ice mold is selectively received on the conductive ice mold and covers the vertical opening. The insulator ice mold defines an internal water passage extending above the mold cavity in fluid communication with the mold cavity. The external insulator jacket is selectively received on the insulator ice mold and covers the internal water passage.