Will copper turn my skin green?

It could. This is a natural reaction called oxidation and is not a reflection of the quality of metal and often has to do with your body's PH levels when you sweat, or your natural oils. In order to minimize this, we apply Renaissance wax, but these waxes are not permanent & can be reapplied should you need to. You can also apply clear nail polish as a barrier. For some, none of these methods will work because of their body's PH, but the oxidation is not harmful.

If my silver tarnishes, is it an indicator that it's not real sterling silver?

No, it's not. Many metals, including silver, can tarnish over time-thus you've heard ones talk about "polishing the silver" in shows and such. Tarnish is an effect of oxidation, not a reflection on the quality. We oxidize many of our silver pieces intentionally to give them a tarnished or rustic look. We use at least .925 sterling silver, and in some pieces we use .999 fine silver.

How do I know my ring size?

There are few ways to determine this, but the best two ways are to either pop into a local jewelry store to have your fingers sized or you can purchase a ring sizer measuring tool. They are pretty accurate and inexpensive.