Sheree, if you go to stained glass and mosaic forum, they would know what you could use. I have done some garden crete edgers, but I used tile and then grouted, they turned out really nice, you can look at them if you go to mymember page and visit my webshots album. Sorry I couldn't help more.
bonnie

Here is a link that might be useful: stained glass and mosaic

Sheree,

I used this approach as well. ( 12X 12's ). I used Welbond to adhere the pieces then grouted. I let the grout cure for nearly a week ( not sure that long was necessary) then grout sealed with a commercial grout seal. This was all an experiment in my case. Others may have sage advise on its success.

These were intended as purely decorative and not for walking. The thinner layer of grout you apply in this technique might not with stand the traffic.

While I had no problem... in retrospect I might select a outdoor caulk next time to adhere the items. Welbond is great stuff... but I've heard mixed reviews on its ability to withstand moisture over time. Hate to see the work disintegrate!

They withstood 1/2 of a New England winter outside (shame on me...Autumn stepping stones at Christmas!!)

Found this link when I googled for mosiac stepping stone - seems just what you're looking for.
Good Luck.
lu

http://www.abc4.com/gtu/featured_guest/story.aspx?content_id=3A189DDA-D1B4-482D-A7BF-81BA8D0DE17D