Sequins will do that. There's no avoiding it unless you want to gloss each individual disc with clear nail varnish, and that eventually chips off too.
For gluing them on, I recommend latex weft glue. This is the type you use for hair extensions, but is stronger than eyelash glue. You can buy it in Sally's. It dries white or black, depending on the type you buy.
There is also a weft glue called "liquid gold" which is great for extensions, but likely to pull the backs off your tassels and half your skin when you peel that off. Best avoid that one
