I have used two types of scribers that work well. One is made by General Tool Mfg. Co. in New York (most well stocked hardware stores carry General Tools) and is part # 88. The scriber has a Tungsten Carbide point that’s useful for scribing stainless steel, ceramics, glass and magnets. The scriber # 88 has a screw chuck for reversing the point when not in use and has a knurled aluminum pencil like shaft. Many times when I build a custom pickup I put my initials on the magnets for dating and future identification. There are also diamond tipped scribers but they cost much more. Using a monocle I can scribe my initials so small it’s hard to see with the naked eye.