If it is white gold it is only plated white gold, IMHO, if you look really close you can see the plating flaking off, especially on the muti-strand piece, it's hard to tell from the photo if the same is happening on the solid portion of the piece.
To confirm if it is or not white gold plated or solid, you can take it to a good jeweler and have it tested.
Thanks for the extra pics, and I can't tell if it is gold or plated, but it does look like a 'twist' ring. They have been made for centuries and are still being made today. You can see lots of pics by GOOGLING.