'Spark!' was based on my 'String' series of vases from late last year - or two years ago, if you're reading this on Thursday!
'String' series vases are made by using two stripes of blue (or green) to highlight one sandblasted stripe - you can see its influence on a lot of my recent work. For 'Spark', I reversed the setup by sandblasting the stripes and keeping the rest blue. The result was a LOT more light coming through, and a really energetic look. :)