what gem would control the wind like Lapis does?
This is a fun ask, because Lapis Lazuli doesn’t actually have established connections to water—it’s actually an air stone. This means that, even taking the show’s framework as immutable gospel (which I wouldn’t usually recommend), you’re totally allowed to choose any stone or crystal that you think looks right! I don’t have any particular gemstones in mind, but here’s some advice for your own consideration:
Think of colors you associate with air or wind and use Gemdat to find gems with those colors.
If you see a gem with a cut (shape) that reminds you of air or wind, you can use that stone or take inspiration from its cut for your design.
You can look for gems with air connotations, of course! A quick Google search for “air gems” gave me this and this, and there are definitely more places to find similar info.