Add the sugar, glucose syrup and 100 ml (approximately ½ cup) of water in a large saucepan, mix well and heat slowly while stirring until the sugar crystals have dissolved. Raise the heat and bring the mixture to a boil. Check the temperature with a candy thermometer to. This should be 140°C (approximately 284°F) hot.
When the temperature has reached, immediately take the saucepan off the heat and stir in the violet oil and violet food coloring until desired color has reached. Pour the hot mixture carefully into a mold (20 x 20 cm) (approximately 8 x 8 inches) lined with baking paper.
Sprinkle with a little sugar and refrigerate. Cut the fully chilled candy block into pieces.