I painted the background with a mixture of winsor green (blue shade) permanent alizarin crimson, and burnt sienna. I used the wet into wet technique, to allow the pigment to float and create some highlights, rather than painting a flat black background.
I will be teaching this lesson and more at the Learning Products Expo in Chicago. The name of the workshop is "Watercolorist Guide to Painting Crystal & Glass", it will be a six hour workshop on Saturday, July 11, 9-4 PM. For more information on this workshop visit learningproductsexpo.com Hope to see you in Chicago!