Burnishing

Burnishing gives clay a natural sheen.

Step 1 — Wait until the pot is leather-hard to almost dry.
Step 2 — Rub the surface with the back of a spoon or a smooth river stone in small circles.
Step 3 — Work section by section until the whole surface glows.
Step 4 — Repeat once more as it dries for a deeper shine.

It takes patience. So does everything worth wearing an evening gown for.