Sharpie paint pen
On my favorite Model 25-2, the original owner had a gunsmith drill into the front (ramp) sight and insert a white resin rod, which has gradually become a bit discolored.
While trying to decide whether I want to pay the $$$ to have the sight milled off and replaced with a pinned-on gold bead, I've in the meantime taken a white sharpie fine-tipped paint pen and brightened up the rod.
Certainly not the most elegant solution (either the original or my update), but it works pretty well for now.
Side note:
Just out of curiosity, does anyone know what I might expect to spend to have the sight milled and a pinned sight put in? (And is this something I should send to the "big" gunsmith shops, or would someone local likely be able to handle it?)