Magic Forums

When doing a spell, is there any way to substitute an ingredient or object? For example, In a Spell, it called for a smokey quartz gemstone could you use any kind of quartz?. And in another Spell is calls for Sprigs of Rosemary, could you use ground Rosemary? I'm sorry for asking, but i just would like to know if a spell has to be followed as a recipe or if there can be improvisations.

Thank you.