When engraving sterling silver or other soft metals that are perfectly smooth, do NOT use a fiber-tip permanent marker for guidelines. Often, the fiber tip has an abrasive quality that you’d never know was there until you make a baseline with one. Sterling and other soft metals will be scratched and that scratch, though faint, will show and not come off with alcohol. You’ll need to use Brasso or Semichrome. Both are metal polishing compounds that will usually remove the scratches. Here’s how to draw a better/safer guideline: String a piece of clear tape…..3M FROSTED is best…where the baseline should be. Put a bead of color, about 1/4th the size of a small pea, on the edge of the tape. Be sure the tape is burnished down tightly on the surface. With a cotton ball, rub the color all along the edge of the tape where the g/l is to be. Rub until there is no sign of color above the tape; the surface you’re about to engrave should be totally free of any color before you remove the tape. Peel up the tape and there is the razor-sharp, hairline that is now your baseline. If the metal is textured, or has a slight ‘tooth,’ you may need to wash out the color that is caught on the rest of the surface, after you’ve finished the engraving.
This same approach is perfect for almost any other surface you engrave. Do NOT use on wood, frosted glass, or any other textured surface. Gotta be perfectly smooth!