Crystal Ball of Knowledge

From UOGuide

The Crystal Ball of Knowledge is a quest reward given by Ortlem the Mystic upon completion of the A Mystic's Journey quest at the alchemy shop in Ter Mur.

It has the same functionality as the Skill Tutor Statuette.

Difficulty Ratings

Note that the difficulty ratings are gathered by comparing the message with the crafting chances.
If you get the the too challenging or too easy message you will have zero chance to gain skill from that item.
Optimal means what you are doing gives you your best chance for skill gain. Every other message falls somewhere between.

Difficulty	Success Chance
Too Challenging	<1%
Very Challenging	1% - 20%
Challenging	20% - 40%
Optimal	40% - 60%
Easy	60% - 80%
Very Easy	80% - 100%
Too Easy	>100%