I might have one of these woven up somewhere in the stash . . .
For now we’ll make do with just the diagram.
Update 27 April 2020—I found a sample of the solid heart. I can’t tell exactly how I warped the loom; I know I did three layers in dark purple and one in light purple, but I’m not sure which is which. (Taking a stab, I think L3 in light.)
The thing I like about this square is that, with the ends worked in as you go, it gave the square a nice dark border on either side of the heart. I’ve never made a coaster, but this might be a nice accent for one, or for something else.