At the start of Resident Evil 3: Remake, you need to find three different colored gems in the game. The first one, red, is relatively easy to find. Blue is a bit more difficult to locate in the game and could take you a while to locate, especially if you're not careful. The Last Green Gem is also a bit difficult to identify for those who could quickly pass it and miss a critical part of the game.
You won't be able to access the Green Jewel unless you get the bolt cutters and the hook in the game. You receive the bolt cutters as you progress through the game, just before you meet a handful of UBCS members After this scene , and you continue further in the game, you will descend a small staircase where coarse webs resembling zombies develop. At the bottom of a path to the left of the stairs, you should see a body containing a small container. Grab get it, watching a disgusting cutscene afterwards, then examine the box in your inventory for the lock pick.
Now with the hook in your inventory you need to go back to the start of the area and come back to where you needed to use the fire hose to burn the flames. Go back to the front of the area where you can find a toy store. It has a lock on the front, which you can use your hook to access. A short distance from the entrance is a small jewelry box. After examining and opening it, you will find the green gem inside.
Once you have the Red, Blue, and Green Jewel in your inventory, you can bring it back to the Clock Tower Monument to receive your reward. Make sure you grab them all to receive all of the available rewards inside.