The key is to capture the micro‑reflection of light on each facet of the surface, just like a steak's sear catches a glint in a pan. I would map the grain pattern to a layered metallic shader, then tweak the specular highlights so that each spice particle glimmers like a tiny, polished shard. Precision in the normals and the light fall‑off is what turns a digital cut into a feast for the eyes.