Convex, not flat. Much cheaper than repainting your dial, also you'll keep the original one.
Omega Dial for 565 Geneve Dynamic 30.4mm
Rolex Quickset DateJust 36 Custom Red Dial For Ref. 16234 16014 116234
28.5mm Red & Silver Watch Dial for SEIKO NH35 NH36 Watch Movement
Rolex Quickset DateJust 36 Custom Red Vignette Dial For Ref. 16233 16013 116233
29mm Red Watch Dial for SEIKO NH35 NH36 Watch Movement Parts