minecraft-assets/assets/minecraft/models/block/polished_diorite_slab_top.json

{
  "parent": "minecraft:block/slab_top",
  "textures": {
    "bottom": "minecraft:block/polished_diorite",
    "side": "minecraft:block/polished_diorite",
    "top": "minecraft:block/polished_diorite"
  }
}