The first two pictures are of mesh tops with knitted designed braletts on them. The two below are some modern day trends inspired by the top 2 pictures of Miss Stefani.
The third picture of Gwen Stefani is her in a white knitted like sporty bra/ crop top. A lot like the one Jeremy Scott (Moschino) designed for his recent line. Celebrities like Rita Ora or Nicki Minaj can be seen wearing these trendy itty bitty little tops.
You can find these pieces on:
nastygal.com
dollskill.com
neonsaints.com