I'm referring to something like this:
Or they are just called jewelry?
English Language Learners Stack Exchange is a question and answer site for speakers of other languages learning English. It only takes a minute to sign up.Sign up to join this community
I think it depends on the type of jewelry. Those look like beads or sequins, possibly both. From M-W:
Definition of bead for English Language Learners
: a small, usually round piece of glass, wood, stone, etc., that has a hole through its center and that is put on a string with other similar pieces and worn as jewelry or that is sewn onto clothing
Definition of sequin for English Language Learners
: a small piece of shiny metal or plastic that is sewn onto clothes as a decoration
I found a link with this particular picture and they call the dress "Champagne Beaded Prom Dress".
As @m_a_s points out, there are also rhinestones:
Definition of rhinestone for Students
: a small imitation gem used in jewelry or for decoration