(An oversized rice sack filled with fist sized gems.)
"Use these low quality gems as bait."
Ha..?
I mean, even if there's something wrong with the cut (though I'm not sure why nobles would hoarding flawed gems; Then again, I'm also not sure why they'd have an entire storehouse's worth of gems to begin with, either), they seem to be superb enough in carat, clarity, and color to still make them quite valuable.
There's definitely merit to giving him a reasonable amount of funds, as he'd be seen spending copious amounts of money if he's ever tracked, which'd make any statements he makes regarding the quantity of loot present in the warehouse extremely suspect. It's a great way to divert attentions from the truth of the matter. That said, the "low quality gems" line just really doesn't seem to match the choice of art.
Moreover, unless gems are seriously devalued in this kingdom (which is plausible, they have managed to build up an entire warehouse of them, after all), that'd be an absurd amount of wealth to give up, even for the sake of a ruse. Which doesn't necessarily mean it's the wrong choice, but it really does raise the liklihood that the art isn't properly representative of the actual circumstances. Well, alternatively, it could just be that a "fallen noble" still has a rather phenomenal amount of wealth to work with, and that sack isn't all that significant to the whole.
Really, there's just a lot of questions raised, there.