High-quality vitreous glass, the colours are more vivid and intense than the standard vitreous as the base glass is pure silica. This collection contains hard-to-find colours that round out the palette at a very reasonable price. High temperature vitreous glass. Gorgeous fine-grained surface texture that catches and reflect lights. The tiles cut evenly and cleanly with a wheeled nipper. Each tile is 20x20mm and 4mm thick.