Is 18k Gold plated jewelry worth anything If so how much per karat?

24 karat gold is pure gold. So, 18 kt gold is 18/24th's pure or roughly 75% pure gold. If Gold is selling for $1000 an ounce, $750 an ounce might be a fair price for 18 Kt gold. Much of the gold used in jewelry though has other materials that are valuable. Platinum is in much of this gold (as an example). If this is the case $990 an ounce for this gold might still be very low in terms of real value. The best method is to take your gold to a local appraiser and get a fair market evaluation. NEVER send your gold to a broker in the mail, unless you don't care what you get for it.