Language of it's own
Kathy,
Photography has a language of it's own. Digital even more than film. Most of the photographers here are of varying interest and experience levels. And most are quite helpful.
Your camera has image stabilization, but, regardless, for products a tripod is best. The cameara up close needs to be steady to capture the jewelery at it's best.
Also, the way your camera sees the color differently than your eyes = "white" is different than your eye sees it. If the light is not the right "temperature" it will appear blue, green, yellow, orange in the photo. There is a way to have the white appear to be WHITE by using tools. A grey card (available at the photography store or on the web) will help your camera see the color the way you want it and it will allow you to process the photos to be the right color since it is like a measuring tool.
Light comes in flavors. Flourescent is one kind and it has a color cast in imaging; Tungsten is your regular light bulb usually; Flash on camera gives a different tone. Too much light takes detail away and too little will make your jewelery have no color or pop. The temperature of color is actually measured in a standard called Kelvin. Sunlight and shade all affect how the camera sees color too.
Yes, you can be too close and your image will be out of focus. You can also have the lens opening set to let in too much light - called low depth of field. It makes it fuzzy - which is something a lot of people use to highlight their subject.
What you are attempting is not a beginners task. We're all willing to give some input. It takes some patience to get from point a to the end result.