Abstract: Apparatus and processes by providing for gradually interleaving layers of zirconia powders having different concentrations of colorants and yttria to obtain color and translucency gradients that more closely mimic natural teeth, in which apparatus includes a comb having a multiplicity of tines that is extended vertically into a mold configured to hold at least two layers of differently constituted powders, such that adjacent layers of the powders form an interface. The comb is reciprocated to create a textured surface pattern on a topmost layer of powder and additionally may be used to penetrate an interface between adjacent layers, thereby redistributing the particles near the interface. In alternative embodiments the comb may be coupled to a geartrain configured to drive the comb along an epicyclic path when redistributing the particles near an interface.