Kim and Kyle Richards -- Reunited, and they Feel So Good (VIDEO)

Kyle Richards stunned everyone Saturday when she took her estranged sister Kim to dinner for her birthday.

Kyle has put a tough love wall up between her and Kim since she fell off the wagon in Mexico several months ago. Things have not gotten better for Kim ... she was arrested for shoplifting at Target.

But all seemed well outside Ocean Prime in Bev Hills -- at least on the surface.