Well, I've seen worse. Many of the jewelry items are dark. Do you have a flash? If close-up pictures with flash are too bright, dial down the flash setting if possible, or put a layer or 2 of kleenex over the flash.
Many of the small items are out of focus. Check your focus/autofocus on the camera. Make sure it is focused on the centre of the item and use enough depth of field so that all of a round or large item is in focus. In a few cases your depth of field is too shallow. Use a smaller aperture setting to get more of the item in focus.
Try a close-up/macro setting if you have one, for small items. Use a tripod or brace the camera on something if your hand-holding is shaky.
Plain backgrounds with neutral colours are best; you have mostly done that.
Pix of small items like the vase & figures that have shadowed areas would benefit from a reflector on the shady side. Try a sheet of crumpled aluminum foil. Or, photograph outside on a cloudy-bright day.
Mostly you (or the camera!) are missing focus, and the lighting is low. Addresing those problems would improve the pix.
Hope that helps a little. Good luck.
