Can the rose gold diamond bracelet be worn in the shower daily without turning colors?

I've actually had mine since Sept 2021 and it does have a worn look (which I actually love vs it looking brand spanking new) and some of the rose gold coating has faded revealing the silver beneath. But honestly, it doesn't bother me at all. I love when my jewelry look old and lived in. I've just purchased the gold one to wear alongside the other one.

Who is the actual manufacturer and shipper of the MK brilliance bracelet

The Michael Kors Women's Stainless Steel Bangle Bracelet with Crystal Accents is manufactured by Michael Kors and is being shipped by Amazon.com.

Are you able to swap out the charm?

The charm is not interchangeable.

Would like to know the diameter in centimeters.

This is a somewhat rough estimation because the bracelet is more oval shaped than circular. The circumference is approximately 17.8 cm, and the diameter is approximately 5.7 cm.