The first step to make the ice cube look more realistic is adding a Volume inside the ice block to recreate the foggy central part of an actual chunk of ice. Using the Voronoi texture, the artist creates a bumpy, uneven surface. To control how see-through the shape is, he sets up a Color Ramp and tweaks color settings towards darker shades to create a shiny, glassy, transparent appearance. Through Displacement settings, the artist controls how chunky the ice block looks.
He then creates node groups for the material, where all the essential settings can be easily changed in a couple of clicks to customize the look of the ice cube.
You can get the Ice Cube Material on Ryan King's Gumroad. It comes joined into custom node groups, so you can tweak several settings (color, displacement, roughness, etc.) to experiment with the material and get the desired look.
