Crystan, you'll find diamond in the Gemstone material drop-down list, which will set the IOR for you. Personally I do not set it to Hyper Realistic.

There was a setting for Pearls but it was on the old Daz site, so cannot find it for you. There is a IOR setting for pearl in the same drop-down list though.

Sharkbyte, funny how we both rendered redheads with the simular poses.