The red sharpie trick does work. What I used was a "marks-alot" marker. I took the back of the marker off and dropped the ink holder out, then squeezed a few drops of pure ink on the lense. I put the marker back together and used the writing end to spread the ink around, it was kind of self leveling. Do it quick because the ink dries fast. You end up with a clear red piece of glass. I had the afore mentioned marker on hand and it was easier that sourcing Dykem, but I imagine the results are about the same.