Doctor Lautrec and the Forgotten Knights

Hi everyone and I am currently playing (and enjoying) Doctor Lautrec, but I have noticed that there are about four or five treasures that can only be obtained via Jewel appraisal.

I was wondering if anyone could give me their favorite locations for mining the rarer jewels (i.e. the ones on the last row of the list in the appraisal office) Is there any particular quest or quests I should play to get lots of them? I really want to make sure I get all the Treasure in the Game if I can.
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Kratos: "This isn't a field trip you know."
Phoenix Wright:"You're lying dammit and I can prove it!"