This ring I got here @ Rendo:

http://www.renderosity.com/mod/bcs/diamond-finger-ring-tiffany-setting-01-for-poser/55109

Originally meant for Poser I believe, but it works & fits well on her Left hand(camera Right when she's facing me) and on the Ring finger in DS4.

But one thing I've been doing is adjusting the fit from the default apply setting in fine tuning the adjustments slightly so it fits on her ring finger perfectly. The top 4(3 Translate + 1 Rotate) parameter settings are changed very slightlyso it fits all the way through her finger & rotated straight upward or outward depending on her body angle. I move her around above & under to check for perfect fit & after those minor adjustments, it does indeed look perfect.

Her hair fits & stays on her head even when she's doing all kinds of poses, so I'm not sure why the ring hasn't been staying put. I never parented the hair to her head, but it stays on anyway through every pose.