I just hit a total of 25 MMs (not counting Sub MM's) and was surprised to find I didn't qualify for the Ruby MM badge, thinking I was sure that I had read somewhere that I would. So I dug around a bit and found Bok's comments below
I didn't spot it before when I read that, but the break points of these badges are a bit confusing, is 25 Emerald? or is it Ruby? My gut feeling is that getting to 5,10,15,20,25,30 and 35 is more noteworthy and worth a change of badge than getting to 6,11,16,21,26,31 and 36. I am not campaigning to get the ruby badge, but I think it is worth checking out the coding to make sure it is the way you want it.