In DragonVale for the Android & iOS devices (iPhone, iPad, etc.), the Firework Dragon is a limited dragon that is only available around the 4th of July.
The Firework Dragon has a base breeding time of 6 hours, sells for 750,000 coins, and earns 12,500 XP for successful breeding once you reach level 14.
To breed a Firework Dragon, you just need to breed a Fire type with an Air type dragon.
Need lots of gems at a cheap price? You can actually buy DragonVale gems on Ebay.