To get the Sapphire crystal you must go to four island and enter Icefall Cave on the
far end of the island. Have a pokemon that knows Surf & Waterfall in your party to climb the first waterfall you see. Once you climb the waterfall you'll find a ladder toward the left side of the screen. Go down the ladder and you'll see an oppening. Go through and you'll find Glacia preparing to battle some Rockets. Join her and defeat the Rockets. After defeating the Rockets exit the cave. Now go to six island with a pokemon that knows Cut. Venture down toward a place called Dotted Hole on the map. Once there find a door that was once immovable. Use Cut on it to open it. Drop through the hole in the middle and then the hole toward the top, left, right, and bottom in that order. There you'll find the crystal, but someone steals it! He flees to the Rocket Hideout onfive island. Go there, defeat all of the Rockets, and talk to the theif. He'll give the crystal to you when you reach him!!!! Happy to help! :]

- Ash