Quinzième anniversaire
Joyeux quinzième anniversaire (it's the same sentence for a man or a woman)
15 th year anniversary
This would be your crystal anniversary.
Crystal is the primary material for the fifteenth anniversary with glass as the modern material and watches as the alternate modern choice.
Well the anniversary names are usually derived from gifts that are given on that year, for instance 1 year is paper, 10 years is tin, or aluminum, 15 is crystal, and 20 is china.
quinze septembre
The Titanic's 100th anniversary will be on April 15, 2012.
J'ai quinze ans. Direct translation: I have 15 years. (I'm 15.)
We say '15 heures' or 'Trois heures de l'après midi'. But '15 heures' is better.
Sept heures quinze
15%
I've seen this coin in good shape go for $11-15 on eBay.