Regarding my "fly photograph" - yes, it was a BIG bush fly. So to get back to the topic of this thread, I've attached a photo of jewellery using the same technique.
Set the camera on close-up (which is flower icon on my camera), and go as close to subject as possible without the subject becoming blurry. I do this by half despressing the shutter button for automatic focusing.
This photo wasn't cropped, however, if it was it would appear even bigger again.
I find natural light better than flash, and as Woody32 mentioned, backgrounds do play a part.
Les