Here you will find some great t-spline heads.  There are some 4 prong heads along with princess and marquise heads.  Even if you don't use these parts in the final piece they are great to render with because of the rounded edges.  You'll love working with these.  One of my favorite are the fishtail heads that can easily be adapted to your needs.  Just orient object to stones and it lines up great.  Just another quick way to build something.  Oh and lots of heads have symmetry applied to make it easy to adjust.  A total of 31 heads. 

A small video on how to use some of the heads in the HEADS LIBRARY