What would be the best result of a ring/amulet caster roll, and what are the conditions?

I'm reading https://diablo.fandom.com/wiki/List_of_Caster_Items

It seems for materials I just need:

• Magical ring/amulet
• Jewel
• Perfect Amethyst

However, what would be the best (or at least acceptable) roll result (so that I know to keep it)?
FWIW, I have found Mara's and Manald. I wonder how the best caster ring/amulet compare to these.

Also, what's the condition (e.g. player level, item level) in order to achieve the best result?