These are one of the same markers I use to mark the edges of the tools I need to sharpen. A small investment buying a marker saves on tool steel long term. By marking the edge and then testing it against a grinder stone you can eliminate errors in setup and lengthen the life of your tools.  Also great for anyone who needs a black marker!
 
BIC Marking 2000 ECOlutions is a versatile Permanent Marker that is quick drying and can be left uncapped for up to 1 month without drying out, making it perfect for use at home, school or the office. The alcohol-based black ink will stand out on most surfaces. It dries quickly, has a low odour, and is resistant to fading. The tip will not dry out even if the cap is left off for a month, making this a Permanent Marker that will last you a long time.