I would seriously would had considered this a hybrid with Begonia Escargot.
The similar characteristics of colors and foliage formation is undeniable.
However, this one is smaller and much compact compared to furry former.
This plant is sturdy and robust. I find that this one is robust and able to handle stress well compared to many other Rex. However they don't like to be touched or handled as the leaves are fragile and crispy. If you would fold the leaves, they would snap with water coming from the leaves - unlike other types of foliage this one is not flexible.
However, the plus point is the silver iridescence that shines like silver with green center and slight green lining. I had checked few times and found that there is a slight spiral formation of the leaves, almost like a fold in between two leaf edges.
Do handle with care as they can snap and break easily.
The shaded counter-part don't fair well. The sheen faded and barely surviving.
I'm guessing this one is a sun lover rather than a shaded one.
Begonia Common Names and Images
Here is the link where I had put together a list of all the begonias that I had come across. A database of all the different types & their characteristics. Please click on the link on the title above for the post.