I have squash blossom necklace with a makers mark of RB can anyone help identify the maker.

This is more than likely to be the indian maker "Running Bear". I have and have had quite a few pieces of this artist work in my collection of torquoise jewellery. You can have a look on my Facebook page. Hope this helps from Vicki at "Tatanka Torquoise Jewellery".

It could also be one of these
* Richard and Rita Begay
* Robert Becenti, Jr.
* Raymond Begay
* Jamison Ben and Harry Yazzie
After more research I have found that if the makers stamp is just RB then it is probably Robert Becenti Jr