Jewelry Store tasks you with stealing bags of jewelry from the store and loading them into the van. You'll have to secure either three or six bags, depending on the difficulty.
This can be the easiest, quickest job in the game if you move quickly. The fast track is to immediately run into the store while putting on your mask. Force any patrons inside the store to the ground, smash a glass case, and bag a set of jewels. You're now ready to take the bag back across the street to the van. If your whole team does this fast enough, you can load four bags into the van in under a minute. This satisfies the quota on easier difficulties, but even on higher settings, you're left lacking only two bags. Keep up the pace, and these can also find their way to the van before any police arrive.
Should the cops arrive, your driver will leave to find a new loading spot. During this time, bag up the remaining jewels and leave the bags in the hallway in the rear of the store; if you're feeling brave, they could also go through the window into the alley. Keep an eye on the bags until your driver returns, then grab the jewels and book it.
Should you wind up in a shootout, the office in the rear of the store is a good place to camp. In here, you only need to watch one doorway, and the large desk can serve as cover.