Easy first go up to mt ember on one island then go to where there are two rockets battle them and then go through the hole find your way you find it
if u mean the ruby it is on one island after you beat the Pokemon league and have the national pokedex.
1 island 6 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
Head north on Island 1, and keep heading north until you see two rockets. You must have defeated the Elite 4 and gotten the National Dex.
use cut. ;)
at mt ember after fighting the rocket grunts and going in mt ember
FireRed. If Ruby, Sapphire, and emerald you must have Ruby and Sapphire gem and give it to celio in one island
mining it
after u battle th first gym leadr
The gem is on six island not seven island and its inside a cave called dotted hole.
After you have obtained and restored the Sapphire gem, you now are given the ability to trade with trainers from the Hoenn region. Mind you these need to be your real life friends, and they can give you all the Pokemon from Ruby, Sapphire, and Emerald.
You can go back to one island and go to mt ember and get a Ruby gem give that to celio and he will give you a rainbow pass giving you access to islands 4-7.