Google "Garden State Brick Face" It's a stucco technique these people have been using since wwII. I remember their commercials from my childhood in NY. The problem I foresee with your plan for tessellated units is they will not be particularly flat, and they will dry to a different size than when they were wet, complicating the seams, and the color may not be consistent batch to batch. z-brick had the advantage of scale, meaning conditions were very controlled and uniformity was assured, and they made them one at a piece, not any interlocking thing. Another idea to consider is Eldorado stone, but these products are a bit thicker than your 1/2" target. I believe that you could possibly learn how to do a rock-faced stucco, but I have doubts about casting stone sections. Casey Here is a link that might be useful: Stone face

It would not look weird at all, as you say it would be more consistent with the rest of your windows. I think that is a great idea. While I like the colors you have chosen for the slate, I dont think I would like the square tile, I would prefer the random sizes, more natural looking. Hopefully someone can do some photoshopping for you.

Hi After removing some of the stone, (replace with Stucco) I wonder if I made my home more vulnerable to fire. And whether the kerb appeal will change for the better? Any thoughts welcome.

I would not do something based on current fads. I design by classic elegant design principles becuase they remain elegant always. ie, Channel has not gone out of style! The color of the stones should match their environment and the style of the house. A modern house would never do with orange stones. a woody, midcentry modern house might. not orange- ever- but natural stones that are warmer- tans, etc. If one is selling a house this year, and doesn’t care about the long term design quality of the house, I can see going with what is popular but...I still wouldn’t choose something just becuase its the latest fad. I have a girraff wall that was popular at the time, but does not at all go with a grey victorian house, nor does it reflect the local color of the rocks. its horrible. if i had had more money, it would have put me off buying this house becuase replacing the retaining walls is too expensive a project for me now. but I have to look away when I pass them.