Cinelli vai bianca stem bolt sizing

Lord Jimmy 7th
Lord Jimmy 7th Posts: 379
edited March 2013 in Workshop
Hi, I am trying to get some replacement bolts for my stem because of winter they appear to have gone a little rusty, but I am struggling to work out what size they were? They appear to measure at 4mm diameter for the faceplate and 5mm for the steerer bolt. But I thought that they would be m5 and m6 bolts and so should measure 1mm more? Am I missing the thread when I am trying to measu (with a ruler by eye).

Has anyone got the same that could check?