For all uncountable nouns, there are these three possibilities as you mentionned. However, please note that in the second example : "Je veux un café", "café" here actually refers to a coffee cup. You mean you want a coffee, just like in english, you can't count coffee but you're referring to a coffee cup. So, that means you can say: "Je veux une viande" or "Je veux un jus d'orange",... They all refer to a "portion" of it. It doesn't work for all of them you can't say "Je veux un/une or" (or = gold). You can say "Je veux de l'or" but you can't count it so "un/une" doesn't work. I know it works for some of them (mostly food) but to avoid confusion, add a noun that expresses the quantity --> "Je veux un lingot d'or" or "Je veux une pièce d'or"... If you want to read more about it : http://www.lebienparler.com/cours-de-francais/lecon-de-grammaire-francaise/apprendre-le-francais-en-ligne-gratuitement/mots-et-groupes-de-mots/nom/cat%C3%A9gories/lecon/cat%C3%A9gories-noms-d%C3%A9nombrables-et-noms-non-d%C3%A9nombrables Good luck in your learning adventures ;) have a good day sir