Fluorite is use for rerolling the affix value.
I think your thinking of Sapphire it rerolls the affix to another affix.
What affix are you looking for?
But usually that is the case because we have a lot of epic affixes and just get 1 option after using sapphire.
It usually takes a lot of sapphire to find what specific affix.
Remember you can't stack same affixes.
Like 2 epic luck affix.
Or if your weapon has a Legend ED% and your trying to get epic ED%