If you've ever sent jewelry somewhere, you know how worrisome it can be. However, there are a few simple precautions that can make the experience less stressful.
Package your jewelry securely in an appropriately sized box. When possible, use a box designed to hold the specific type of jewelry you are sending, since this will hold it securely. Otherwise, wrap each piece individually in cloth, not plastic, and fill empty spaces in the box to keep the jewelry from shifting too much.
Use a shipping method that allows tracking, such as UPS or FedEx, so you'll be able to know when it arrives at its destination.
Buy insurance, especially for extremely valuable jewelry. It costs a little, but it can make the sting of lost jewelry a little easier to bear.