kinda depends on the outfit...some times when the shirt has really heavy and intricate work on the gala part that you would want every one to see clearly, a raani har can ruin the look by covering some of it up and just getting mixed with the colors. it tends to take away from the look of the shirt AND the jewelery.
however if you have a really plain and simple shirt gala, a rani haar can be the perfect thing to wear on top.