How do you get the gemstone ISLAND dragon vale?

You simply buy the breeding cave and select the two dragons you want to breed to try for a gemstone dragon. The only one out right now is the pearl dragonbirthstone, pearl), but to breed it you need the snow and seaweed dragons to put in the breeding cave. Also, you can buy gemstone dragons on the store for different gem amounts. The Pearl dragon can be bought for 1,475 gems. You have to get to a certain level to be able to get it though, although I don't know what that level is. I read that you have to be level 17 but I am currently a level 15 DragonVale player and the Pearl dragon is in the store available for me to buy. I owe all of my information credit to an app I have called "DragonVale Guide". I advise you to get it for future questions. You can also use it to find people who are willing to become gamecenter friends with you! And it gives you information about not just dragons, it also tells you about objects and gives you strategies on how to earn gems, coins, and experience! Just search "DragonVale" in the app store and you will see an app that has a rainbow egg with a background as the sky for its app picture. That is the all-wonderful app! Enjoy! :)