First you need glass working equipment and glass rods. The technique is called "Lampwork".
The roses were made building layer upon layer with pinks in transparent and opaque glass. Then, when having a lump of glass the size of a lollipop, you grab the glass and heat/stretch it to a long cane. When the cane has cooled slowly, you chop it up in tiny stubbs, each giving a slice looking a bit like a rose.
Then you make a base bead, add the little "stubbs" called "Murrini", manipulate them and make them unfold and there you have it, pretty much.
Time.consuming but very rewarding in the end (unless you fail in adding them, dropping them, they crack or otherwise gets distorted by too much heat).. it's tricky but once you make it, it's SO nice!