Think real life - Diamonds are forever. (and worth 180 each)

I only just found three malachite gems (as opposed to the more common malachite ore) and they're worth 2000 each. Two of which were needed for a particular quest…

JDR is right aswell - you'll regularly have bulging pockets. It's hard to go broke in this game, unless you maybe go bezerk on upping the cap on many skills.