The first piece I created using slate and glass was The Circle of Light. What I found amazing using clear, ordinary green house glass was the hidden colours within. This was the first time I had ever looked at the edge deep into the glass and was amazed to see the vast range of colours; green, blue, yellow and a combination of those three. Apparently, so I have been informed, they are due to the different types of sand used when making the glass. The larger the piece, the more pronounced the colour.