Here are a few tips.
1. MACRO. If your camera has a macro setting, find it and use it. It is your new best friend. This setting allows you to get up close and personal with every detail of your gorgeous new ring. iPhones have this setting built in to their cameras (at least the 4s and 4Ss that I know of). It will also bring your ring into focus while blurring the background, which makes your ring pop!
2. Focusing the iPhone camera: Just point your phone at what you want to take a pic of and tap the screen over the part you want it focused on. You will see it adjust and all you have to do is push the camera button!
3. Don't get too close. The iPhone is still a phone, so it's macro isn't perfect. I have found that if I get TOO close, it won't focus, and I also have trouble getting clarity in direct, strong sunlight.
4. Background/setting: This is the fun part! Find some flowers, stumps, trees, ribbon, old books, anything that exemplifies who you are! If you love to read, maybe place your ring on a stack of or between the pages of your favorite books! If you're a nature girl like me, find some flowers to tuck it in to add some vibrancy and life to your photos and so your ring has something to be propped on other than your finger (as gorgeous as it may be!)
Have fun and experiment!! Mine were all edited with Snapseed. Love that app!!