I keep my Instagram follows pared down to a short list so that I make best use of my social media browsing time. @AnokhiMehndi in the West Midlands of the UK is definitely worth following. She's one of the stars of Henna Instagram and this video is an example of why.
Her post doesn't explain exactly why this piece sparkles, but I gather that incorporating glitter into henna dye is a thriving practice. Here are the sparkly arms of @Bharathi Sanghani_Mendhi, who is an accomplished bridal henna artist in her own right.
https://www.elle.com/uk/beauty/beauty-tips/g31619/glitter-henna-designs/