Jewellery - Box Clasp second photography attempt

On the advice of my Jewellery teacher I'm actually trying out natural light photography with my Jewellery pieces in an effort to bring you photos that are a much better quality rather than spending a fortune on proper inside lighting and so on. This will probably be obvious to most photography experts but it was very interesting how much of a difference it made especially to the colour of the photographed Jewellery since everything is natural light, it looks, well, a lot more natural. The only thing I think I need to worry about with this type of photography technique is accidentally casting shadow from my head and so on depending on the angle as I've done in a few cases here.

Despite this though, I think you'll agree the photographs look a hell of a lot clearer than the ones before, all I did was get a dish cloth for a plain background and then started the photography, it could well be it's just down to practice now. Does anyone have any advice on how to prevent the shadow casting issues in natural light photography like this?