Your jewelry can definitely get wet and will be fine, but! For gold-filled and plated jewelry, it may shorten the wear you get out of the piece in the long run. If you do get your piece wet, please dry it off ASAP. What happens with non-solid gold is that water will eventually permeate the layer of gold and reach the base metal underneath. That base metal then starts to leach the metals that patina and change color when exposed to water like copper or brass. This color change in turn is what can cause your gold-filled or plated jewelry to prematurely start to turn colors.