How do you get the saphire on pokemon leafgreen?

to get the sapphire you go to six island and you go to a cave in ruin valley and get to the end then a team rocket grunt will come in and say that the sapphire on the table is his but he will tell you the second pass code for the rocket hideout go to the rocket hideout and beat the admiral and enter the next room you will see the guy who took the sapphire talk to him and he will give it to you