how to clean diamonds set in silver, with color coating?

[KaeKae]

Hi everyone, I'm hoping some one will know the answer to the above question.

To fill in the blanks, my daughter was confirmed a couple weeks ago and received a gift of a sterling silver cross pendant, with little blue and white diamonds. The blue diamonds are set with some sort of blueish or black metal behind, I assume to give the color some oomph. Of course, being a PSer, I know this is not top quality stones, etc, but we both really appreciate the gift, and she loves the style of the cross. Still, it quickly gets dull. I used my polishing cloth on the silver portions, which helps, but is there something we can use on the stones that won't remove the blue metal?

This isn't her pendant, but I think it's made in a similar way.
http://www.jcpenney.com/110-ct-tw-genuine-white-color-enhanced-blue-diamond-heart-pendant-/prod.jump?ppId=pp5003450580&N=752%204294966837&pageSize=96&searchTerm=blue+diamond&topDim=Metal+Karat&topDimvalue=sterling+silver&dimCombo=Metal+Karat|Product+Type|&dimComboVal=sterling+silver|pendants|&currentDim=Product+Type&currentDimVal=pendants&catId=SearchResults&colorizedImg=DP0415201417082082M.tif

Thanks for any ideas you have!

 

[davi_el_mejor]

the blue/black metal is colored rhodium and should be fine for normal cleaning.

 

[chrono]

You are sure it is a metal coating and not foil backed? The care of the 2 are different. I don't know if that is oxidized white gold in the example link.