Got a picture to show...that would help me...I'm a visual kind of person!!! You do make a lot of sense by the way!! I've pondered over things like that also!

How about starting at the edge first? Just google mosaic tables on images and you'll find lots too!
And Squirrelly just did one.

Here is a link that might be useful: {{!gwi}}

I think NT is the Queen of finishing edges. She holds back a little grout, and when she's finished, she smooths the edges w/wet fingers to make a nice finish. If your table has enough on the sides to place a nice-sized tile, bring it just above your table to form a lip, then your table top tiles w/butt next to them, leaving a small grout line. Wish I'd remembered to start w/the edges and do that when I tiled my bathroom counter. As a result, I did the front edge last, and didn't bring the tiles up to match my counter top, and there's that icky line of grout along the edge. Make your own lip. I've seen some artists use copper edging to cover the table edge too. Any kind of tesserae you use, just remember to form a nice lip to the top.

oh, I'm flattered - thanks Slow!... but I figured out my method after continual failure. I like your suggestion of butting the side pieces up to the top - that would really minimize the size of the grout line.

My edge ends up looking like a grout bevel. I stay back off the edge of the substrate about as much as the tesserae is thick, when mosaicing. Grout the piece, but like slow said save some back. Do all my cleaning first (this is where I had trouble because it's the cleaning that knocked grout edges out) then go back with your saved lot and press and rubb the grout off you finger from the table edge to the tops of the tesserae. So you are filling that little inside corner that you created. I will either use my fingers or a dental pick to sculpt it smoothly.

I am doing this with a dryer thick mix, workable like clay