Encountering an armed robber is one of the scariest things a jeweler can experience, but experts say there are certain ­measures you can take to prevent a robbery, or to minimize the damage should one take place, as well as advice you should ­follow during and after an encounter that will help keep you safe. These tips come from the Jewelers’ Security Alliance, insurance ­professionals, retailers, and other industry experts.BEFORE1. Vary your route to and from the store and keep an eye on your rearview mirror to make sure you’re not being followed.2. Don’t open or close the store alone. While one employee locks or unlocks the door, a second employee should watch from a safe distance that still gives a good view of the door. The second person also should have a mobile phone to call the police if the coworker is confronted.3. Observe the surroundings of the store when you arrive.