If you’re planning to stock smart jewelry, consider these key issues of form and function:1. Will the piece compete with a watch? If you’re considering a bold bracelet, ask yourself if customers will give up their watches, or wear both together.2. Will it be too heavy? A piece that looks great in the case could literally weigh down customers. 3. Are there customization options? Some smart jewelry devices let the user switch out settings, bands, and other features to coordinate with multiple looks.4. Can it get wet? This is especially important for fitness and activity trackers, which will likely be exposed to sweat and possibly rain.5. How is it charged? Some devices need to be plugged in, while others have long-lasting batteries that don’t need to be charged. But batteries may not be replaceable and these devices haven’t been around long enough for longevity claims to be pr