Vitreous glass on acrylic, 4" x 4" (10.16 cm x 10.16 cm).  This is truly my first effort, when I had just gotten my nippers and some tesserae and was trying to figure it all out.  A study in shades of grey, I still enjoy looking at it every morning.  Note my complete inexperience preserved for all time - I glued the edge pieces in face down!