I feel still keyshot missing a glittering sparkels specially for jewellery rendering, it will be the best if feature version of keyshot bring sparkel to the high end jewellery rendering.
You need to have small focused lighting to achieve these. Try environments with small lights. If you have PRO you can experiment with the hdr editor. That is how sparkles appear in real gems :)
Thanks a lot sure i will try and hope i get the best result.......