Or maybe you want to unload the trinkets given to you by a no-good lover. Jewelry has been reconditioned and verified for authenticity, and it's usually displayed in nice surroundings.
Pawnbrokers usually traffic in more modest items.
Some brokers make loans on jewelry along with all kinds of other stuff - stereo equipment, musical instruments, guns. When people default on their loans, jewelry is just thrown out on display with all the other junk. Other brokers specialize in jewelry and take the time to clean and recondition it before selling. If you have an item you don't need or want anymore, you might as well sell it outright. Plenty of jewelers will buy it from you, and you could even trade it for something you like more.