You'll first find it in the Dotted Hole on Six Island, but a Team Rocket member will take it to their warehouse on Five Island, where he gives you the Sapphire for defeating him (he has very weak Pokemon).
1 island 6 island
The sapphire is on Six Island. You need a Pokemon to use cut on the dotted door of the cave.
rainbow island
Celo, who is in the lab on island 1
In dotted hole on six island.
in leafgreen u have to get it from a Nintendo event and in sapphire after u get it in leafgreen u trade it from leafgreen to sapphire
If you are going after the Sapphire, then you go to Five Island and run through the Rocket Warehouse to get the Sapphire.
you need the ruby and the sapphire on island 1 so the machine works and you can trade to ruby and sapphire
there is no cinnabar island in sapphire. cinnabar is on firered and leafgreen. also in Pokemon yellow special pikachu edition ^_^ don't forget that dude...
You don't on Island 6. You head to Island 5 and the rocket base where you will find him and the Sapphire.
FireRed. If Ruby, Sapphire, and emerald you must have Ruby and Sapphire gem and give it to celio in one island
you find the ruby in the cave right next to mount ember on island 1. to get the sapphire gem you have get the pass from celio to go to island 4567 and it is on island 6