... is one of those dumb things I say to myself when I'm working on a mosaic. It happens when a piece of cut tile fits perfectly up against another cut piece or when I cut a tile and it just conforms to the perfect shape---usually a curve.
Think about how nice squares of tile line up when they are straight edged and on a grid. Everything is even and perfect. All the joints are the same. But grids get boring and unless you're a Tetris fan, there's not much joy in them. So you get some glass tile cutters and with crossed fingers (figuratively, not literally. Jeepers! Who could cut tile with crossed fingers...?) AHEM, you start to trim those tiny squares into new shapes.
However, they are glass! They don't flex! So cutting those squares into smaller squares, triangles or rectangles is pretty easy....but curves? More hit and miss. Mostly miss.
When all the stars line up and I wind up with a perfect curve (and it has nothing at all to do with skill in cutting and everything to do with luck) I place that curve and think "That's when the magic happens..."
And that makes me happy.
Here's an amazing example from the guitar I'm working on. Not only did the top curve fit perfectly, but the bottom curve goes in the OPPOSITE direction and it mirrors the tiles it's up against. The real craziness is that I didn't cut that blue tile to fit the space. I just cut up a pile of squares randomly and started to see if anything that was produced would work next to the black tiles which were already glued and dried.
What you're looking at is a teddy-bear face. The blue tile is the fur and the black is the nose and eye. It may look like a big gap under the blue tile, but that is a black tile as the top curve of the nose---a lovely fit.