What are the Clear Gems Used For?
The clear gems are easy to find and come into play at the end of the game when if you have collected all of them will unlock The Great Hall gem path leading to the alternate ending which shows epilogues for the bosses, depicting what happened to them after the events of the first game.
What are the Coloured Gems Used For?
The coloured gems are one per colour and are used as links to hidden arenas that will allow you to find certain boxes on specific levels. To find a coloured gem you must pass a level without dying and destroy every box on the level. When you manage to find all the boxes and clear a level without dying a gem screen will appear, if however you have not collected all the boxes a 'Box' screen will appear which will show you how many boxes you missed by dropping them on Crash's head. Just keep repeating the level until you get a 'Perfect'.
How Many Gems are There?
There are 26 Gems in the game, 20 clear Gems and 6 coloured Gems.
How do you Access the Secret Areas in a Level?
To make the path to the Secret Area appear in a level you must find the coloured Gem in the colour of the Ghost Gem. The Ghost Gem will dissapear when you get close to the coloured Gem you are looking for.
Where do you get the Coloured Gems?
Below is a a list of the levels where you can get a coloured Gem, any level not on the list will just give you normal clear Gems.
Blue Gem:
'Perfect' on Toxic Waste
Green Gem:
'Perfect' on The Lost City
Orange Gem:
'Perfect' on Generator Room
Purple Gem:
'Perfect' on Lights Out
Red Gem:
'Perfect' on Slippery Climb
Yellow Gem:
'Perfect' on The Lab