Originally Posted by Neapolitan

I never heard of a "crystal" cup, cups are usually made of paper, plastic, Polystyrene foam, High Density Polyethylene, Polyethylene Terephthalate. Cups are usually disaposable or recyclable (preferably the latter - subjectively speaking), or used for everyday use, e.g. tea cups are usually made of ceramic or glass, while coffee cups are to be differentiate from coffee mugs by volume of liquid thus contained in them. Cups were at one time shared by the public, but at the turn of the 20th century disaposable cups were used instead for for public health reasons. A "crystal" cup has a connotation to it of being a disposable cup made of crystal.

Drinkware made of crystal are sometimes refered to as stemware and are more expensive then plastic polymers, which are meant to be disposable/recyclable, an example stemware made of crystal is a Champagne flute, which objectively speaking is neither a wind instrument nor is used to drink Champagne exclusively. Most likely a non-alcoholic sparkling beverages or a sparkling wines is drunken (drank?) from a Champlange flute. If you want to find out what subjectivity really is try to convince a person, who adamantly and consistently refers to sparkingly wine as Champagne, that they are wrong.