I have found in jewelry photography that sometimes a scanner works quite well. Certainly, depth of field is a problem...but take a colourful stone like opal, scan the stone only...the paste into the jewelry item and you have a beautiful rendering. Or, for the stone itself, try the scanner...believe it or not, it works.  A local news paper ad lady uses a scanner for many of the images for ads  for the place I work.  It works for her and for the business owners.

I developed a cooperation with a fine man in Russia through a website where I take and answer questions about jewelry work..the on hands stuff.  We have commnicated for several years now and he is talented!   The image is Byzantine type chain he made, link by link.  Sure, the chain does not have much depth but the image is done by scanner!   Just one example.        

Thanks for this fine thread.      Your friend,     Tom.