You breed the Willow Dragon and the Quake Dragon on the Epic Breeding Island. You also have a chance of getting a silver or bronze dragon when you breed, but you will just have to keep at it! It helps when your dragons are level 10.
There is a Bronze Olympus Dragon on sale right now on DragonVale if you were talking about the Bronze Olympus Dragon. If you were just talking about a Bronze Dragon then I don't know.
Blazing and Crystal
Olympus bronze Olympus silver Olympus Gold
If you breed any type of dragon as long as they are lv 10 you will get them
Brass Dragon and Fire Dragon
It looks gold
This will be a crystal dragon.
The gold dragon is a permanent legendary dragon, so you can take your time trying to breed it.
2days
You have to either buy it for 500,000 gold, or breed water dragon with another water dragon.
level 14, 50,000 gold
There is no such thing as a Birthstone Dragon on DragonVale