the first thing that popped into my head was to cut them in elongated diamond shape. Use neutrals (perhaps an almond and a soft beige tone on tones) to sash and cornerstone. I think the diamond shape has a bit of royal look to it. This would also work in rectangles, but, if possible, diamonds would be nice. If more of a showpiece than a used piece, even consider sashing of a satin or lacey fabric (Victorian style). Beautiful handwork!