Years ago my wife and I visited Sam Gimignano in Italy. I bought a box of bright blue tessera – the little tiles used as the basis of a mosaic. I occasionally make some earrings using them that usually sell well.
It was only recently that a lady visited my stand during Artweeks and said “I make mosaics and those are tesserae, but that’s the back which is pressed into the cement.”
I’d never given it a moment’s thought – that side looked best so I put it outermost. Of course, the other side being flat sits well in the setting. Few people normally see this side.