The best light for photographing jewelry comes from the shaded side of you home/building/etc.
that, (which I have "cause all my picture were taken indoor "cause our weather's been bad here for 2 months straight) I have a setup where I have two lamps with natural day bulbs and no shades set up on opposite sides of my desk, but anything with an overhang will work like a shelf. Then to the underside of that overhand I taped a piece of tracing paper a couple inches in from each bulb and then tape the dangling ends to the lamps themselves. Sort of a like the tracing paper is cupping the bulb, but nit so close that it will start a fire after being on for a couple hours.
This set up gives you almost NO shadow whatsoever...