2) To glance at someone = To look briefly and quickly, take a look
stringy =  someone who is filiform or wiry
thumb = The short finger in the human hand which is next to the forefinger (index) 
tray = a thin flat board
chalky = something having the color of chalk  = "she turned chalky white"  
to snatch = to seize suddenly 
Nor= it means "not either"
to wrap = to envelop
deerskin= Leather made from the skin of a deer
to thrust= To push quickly and forcibly
fool= an idiot
failure= a defeat
crowd= A large number of persons who are gathered together
to burst= when you "explode inside" because of overwhelming (accablant) emotion
to stride = To walk with long steps
contemptuously= scornfully  (= dédaigneusement, avec mépris)

3) Indeed, the crooks try to make Kino believe that his pearl is a monstrosity. For instance, the second dealer says that the pearl is going to lose its colour and will die in a few months. However, when Kino uses the glass, he discovers  that the surface of his pearl is stunning, we can quote "kino, who has never seen a pearl's surface magnified, is shocked at the strange-looking surface" : and that's why we can also say that the pearl might look so unreal and beautiful.

On the other hand, the dealers offer very low prices:  "I will offer five hundred pesos, and perhaps I can sell it to my client for six hundred", they imply with the word "perhaps" that it is the best price that they can offer. But in fact the dealers are lying to Kino about the real value of the pearl.

Finally, Kino hides the pearl inside his shirt. He feels irritated by the dishonesty and the greed of the dealers. We can find some action verbs, (as « reach » and «  snatch » and « quickly » that emphasize speed), showing that he looks afraid and suspicious of the true aim of the dealer.

Emilie, Célia & Kévin