Ever wondered about the elemental composition of the differently colored versions of glass? Or what exactly does "crystal" glass contain that regular glass doesn't? Have a geochemist bring back last night's empties to the lab. To first order, be careful with the fancy-ware. More iron means more color. And if you need white, try some zinc oxide.
Trace elemental analysis of a big night out
P.S. Of course this is just about these particular elements, and doesn't count the bulk silicon, oxygen, sodium and such.