Take it off when swimming?

I don't believe it matters. Unless it fits tight, I would.

What is the clear portion made out of on the ring? The clear coating that’s covering the gears?

No idea but it holds up well. I used it while lifting weights several times and it keeps it’s shine. With that being said I should have used it while working out

The description says Koa wood... is it actually Koa?

I used to wear a very expensive platinum & yellow-gold wedding band to church or whenever I took my wife out to eat, but after wearing this ring for a couple of years my finger started to blister badly underneath, while wearing it for more than a couple of hours at a time... Hence, so I bought this finely crafted handsome ring that I wear when I go out in public to fine establishments. This Tungsten steel ring has never caused my finger to blister underneath so far and I often wear it all day on Sundays after church. It's such a nice looking well made ring, I love it and my wife really loves it too, the richly colored brown wood part of this wedding band really accentuates my dark chocolate brown eyes as well, or so I'm told... Now, is it really, 100% authentic, inlaid Koa wood? You know, I'm not 100% sure, but I believe this ring's sales vendor's claim that it is... Even, if it isn't real Koa wood, or it's some other type of wood, what does it really matter? I mean after all the sheer beautiful craftsmanship of this ring is truly impeccable to say the least about this product, so why not buy it and see, for the sales price it's well worth the money! Cheers, - RMT, @06-30-2023.