Very carefully....................................
Emo
By this point you will have both the passwords required for the Rocket Base on Island 5. Head to Island 5 and go through the Rocket Base, the Scientist is there.
you go to the dotted whole and you use cut in front of it! Then you go up, left, right, down, then you get the Sapphire and this one guy comes and steels it from you then he gives it back and gives you the last password for the rocket wear house!
Trade it to ruby,sapphire or emerald have them evolve your evee at night then give it back to leafgreen.
If you mean the Silph building in Saffron city - the task is to get the silph scope so you can identify the ghosts in Pokemon tower in Lavender town. If you mean the Rocket warehouse on five island - the task is to defeat the super-nerd to get the sapphire back to give to Celio in one island.
In the casino in Cleadon city. Go the the back where the rocket guy is standing and battle him, then go the the poster he was guarding and press A.
Bring it back to the center on one island by talking to the guy in it. After you can trade with Pokemon Sapphire
You cannot get HM Dive in Pokémon LeafGreen.Since Dive is not an HM in leafgreen the only way to get one of your Pokemon to learn Dive is to trade it to ruby, sapphire or emerald then teach it Dive using the HM then trade it back to leafgreen.
You need to have a Pokemon that knows cut. Stand in front of the Dotted Hole entrance and then use cut. When you get inside, there will be a hole. Go in and then you will need to fall in the right hole and then the Sapphire but a scientist will take it before you take it. Go after him after he tells you the password to get in Team Rocket's Warehouse. Battle them all and they will leave and then he is at the back. Defeat him and he will give you the Sapphire back. Then take it to one island. Put it in and then you can trade Pokemon with Trainers from the Hoenn Region.
no theres not the only thing you can do with Pokemon ruby, sapphire,emreald, firered and leafgreen is you can migrate Pokemon on there but you can never get them back on uroringil ame like ruby and sapphire and so on
Go to dotted hole on six island when your in the cave fall down the first hole then fall down the holes in this sequence: Up, Left, Right, Down. Take the sapphire however it gets stolen from you go to five island and go inside the rocket warehouse defeat the robber who took the sapphire to get it back.
After you've opened the door, fall into the hole in front of you. Then, fall in to the hole at the top, you should land back in the middle. Then fall into the left one, then the right, then the one at the bottom. The sapphire will appear in front of you. Before you take the sapphire this guy will take it from you. To get it back from him go to the Team Rocket warehouse south of Five Island and he will give it to you once you beat him in battle.
To get the Ruby in Pokemon LeafGreen, you need to beat the Elite Four. Then go to One Island and talk to Celio in the Pokemon Center. He will tell you he is searching for two jewels: the Ruby and Sapphire. Go to Mount Ember. If you went there before beating the Elite Four, you saw that there were two Team Rocket Grunts planning to dig a hole in the wall. Those Grunts are gone now, replaced by a cave entrance. Go in and go to the back of the cave. You will obtain the Ruby. Go back to One Island and give it to Celio. He will give you the Rainbow Pass in return for your service, so now you can access Islands Four, Five, Six, and Seven. Go to Six Island and find the Ruin Valley. There, you will find a place called the Dotted Hole. Use Cut on the entrance and go to the back of the cave. You will get the Sapphire, but a Team Rocket Scientist will come and steal it from you. Go to the Rocket Warehouse on Five Island and take it back from him. Take the Sapphire back to Celio. You can now trade with Pokemon Ruby and Sapphire.