Copper oxide is one of the more reactive elements used to colour glass. Within one piece it can vary between deep red, golden grass green, sea green, turquoise and deep sage. This bowl is also decorated with silver nitrate, another very reactive colour, with tones changing from creamy white to silvery blue. Pieces with these colours change dramatically in different lighting. It can be vibrant blue when placed against a dark background and then appear to be yellow and green with red highlights when backlit. Because Peter is one of the few glassmakers in North America to make his own colour from scratch, these pieces have a truly unique jewel tone pallet.