I have been playing with a black light and what I have here is a typical CD 128 Hemingray, a mold date of 40. indicating 1941 in a typical light green. This piece has not been altered in any way and is as it came from the factory. Under black light, it glows a strong, bright pink. I understand that Uranium oxide causes the firefly vaseline color, but what causes this??? Again, this is an as-manufactured, light green CD 128 Hemingray. I have also found 128 Pyrex and some Brookfield pieces that glow firefly. Thank you for your answers and help. Chris