temporary ID marking of flagstones

[office]

Hi, I've got about 150 limestone and slate flagstones of various sizes to l ay to make a patio, Ive measured each one and drawn a 'jigsaw' on screen. I want to be able to mark each stone with a number to make it easy to identi fy them before they are laid and wondering about how to mark them. The mark s will need to be visible for 2-3 weeks. Any ideas?? Thanks

[Vir Campestris]

Chalk.

[Iggy]

replying to Vir Campestris, Iggy wrote: I'll 2nd the chalk. Or, you can put a piece of tape on each flagstone (leave yourself a folded over pull-off tab) and then write a number or code on the tape with a magic/permanent marker. Chalk's still the best, since it doesn't have to be removed manually.