When you have the direct link, .... just paste it in, ...highlight it, ...click the 'Img' button tag above.
Phillip .... I think we're more interested in seeing how the lighting is being setup than the materials.
There's a lack of good realistic reflections here, .... and that hurts both the metal and the diamond. Look, ...you can see there's a lot of solid grey color in the stone ---- not desirable. When you see that, it just means your reflecting something big and plain --- often it's much better to just reflect the blackness.
Also, one of the things that really helps jewelery to look realistic (not always wanted -- if you can believe that), ...is to not always have everything in focus .... get some blur in there. Where's the law saying everything has to be in focus ? ..if it's coming from an art director then fine, ....if not, ....then experiment.
Your still not using -mL effectively ---- everything is just big and bright, ...no contrast. Mix up the emitter sizes and intensities.
If you use such basic setups, your getting exactly that ---- basic renders. Nothing wrong with that if that's what you need, ....but Maxwell is capable to waaaaaaaaaay more. Don't be afraid to add elements via HDR or even home made MXI's (personal favorite) to the render, ..it won't add to the render times and it'll generally make things more interesting. Personally, that's what I'm interested in here --- uniqueness. Forgive me, but any decent raytracer can produce that image above in way less time ---- if we're going to use something that takes a little longer, then there has to be some kind of compensation for the wait and that is supposedly quality. It exists. Don't settle for anything less, because if you do, ..then you should use something else.
Just trying to move you along Phil ....
PS. That ground plane is putting me to sleep --- I think it's the similar coloration to the metal, ...if it has to stay, maybe adding some reflectance and some roughness might be nice.