I work with glass a lot, and have found that epoxy glues work very well when it comes to gluing it. Since this type of glue dries quickly and holds firmly, it usually works pretty well with all types and sizes of glass objects.
Epoxy glue typically comes in two different tubes that must be mixed together to activate the bonding agents in it. Once mixed, it must be used right away because it will dry quickly. This is another benefit of using this type of glue for glass objects, because they hold better when it doesn't take long for the glue you use to set firmly in place.