We had a Denim and Diamonds theme for my 16th birthday party. The idea was for everyone to wear jeans, but also wear our "diamonds" (anything that sparkles) or at least dress it up a bit.
We covered the tables with cloths that looked like denim, and in the center we had a candle and around that we sprinkled craft gems. If you don't have denim tablecloths, you could always use navy. That was our original plan before we found the denim.
We also decorated the room with little white lights and balloons that were silver and navy.
We had dinner and dancing.
Party favors were paperweights that looked like diamonds.