Nyx was one of the earliest colours made by Double Helix and has been discontinued. The glass is COE 104
Working Notes from Double Helix:
Nyx will reduce to a mirror-like or multi-colored luster. It can also be kiln struck for a different effect changing the color from black through a steady fade of Midnight Blue, Lapis, Peacock, Turquoise, and Sky Blue. You can determine the coloration through annealing time, temperature and placement in your kiln.
Tips: We recommend kiln striking a rod of Nyx to estimate the kiln striking time at your annealing temperature. Our kiln striking tests were perfomed between 950 and 970 degrees F. One hour annealing time produced Midnight blue, while Sky Blue tones developed over three to four hours. Higher annealing temperatures push the Sky Blue to a greenish color. Encasing may alter kiln struck color.
Encasing heavily reduced Nyx can produce a mother-of-pearl effect. Speckled and swirled organic effects can be achieved by working the glass very hot before application. Excessive reduction followed by kiln striking can produce earthy caramel tones.