Well I guess if you believe there are unicorns you would believe they sparkle too so yes they sparkle. LOL
I'm almost sure that I saw one once and yes, the one I saw, if it was one, was sparkling. It was on a moonless night and the sparkle of its coat looked like millions of tiny lights all randomly bl<x>inking on and off as though the creature was wearing a skin entirely covered with extremely tiny sequins under multicolored stage lights. It also had a very slight yet clearly present pinkish-violet aura around it that appeared to be oscillating from pink to violet to pink to violet and so on while simultaneously getting brighter then dimmer then brighter then dimmer and so on. There was nothing abrupt with regard to the color transitions or the light intensity transitions and the two transitions were notably neither coordinated in wavelength nor synchronized. Each transition was consistent with its own constant wavelength. Hence, for a second it would appear dim pink, the next second dim violet, then medium pink then bright violet, then medium piink then dim violet, dim pink, medium violet, bright pink and on and on and my description of the aura is still lacking. To properly describe it I would have to include three-part-lighting scenarios: dim pinkish violet then medium violet then bright violetish pink.....can you picture it? I'm not sure my description really grants it full justice. It was captivatingly stunning and mesmerizingly stark all at once. Without question the most remarkable, curious and spectacular thing I have ever seen.
When you put glitter on them yeah ^_^