Is 10K gold good for earrings?

Yes for everyday hoops. 10K is 41.7% gold alloyed with harder metals, so it resists scratching and bending better than 14K or 18K. It looks slightly less yellow and is worth less per gram.

How big is 20 mm on the ear?

20 mm is about the width of a nickel. The hoop hangs just below the earlobe, so it reads as a small everyday hoop rather than a statement pair.

What does two-tone mean here?

The earrings combine yellow gold and a second gold color, usually white or rose, in one design. That contrast is the main visual feature and makes them harder to match with single-tone jewelry.

Are these solid gold or plated?

They are solid 10K gold, not gold-plated or gold-filled. The color runs through the metal, so it won't flake or wear off the way plating does.

Can I wear them every day, including in the shower?

Solid gold tolerates water and daily wear well. Soap and shampoo can dull the finish over time, so rinse and dry them now and then. Check the closure regularly for looseness.