DIY Rose Beads: I made the rose beads from rose petals. They are very dull looking and rough.
The picture you posted of the rosary beads made out of the rose petals look very smooth and are shiny. Mine look nothing like that.
Certified GKH Gardening Expert
Some people have had a LOT of practice. What I see, normally, will be rough or jagged. I think that practice, and trial and error will be the only way here.