Gem

Gems are collectible stones that appear throughout the Crash Bandicoot series. Gems are typically different than the Power Crystals, as in they are more powerful than the Crystals as stated by N. Brio in Crash Bandicoot 2. Whether that information is accurate from N.Brio is a question as it seems that Uka Uka wants the crystals more than the gems since Crash collects these throughout the series. They are usually collected through different means and special tasks like breaking all the crates in a certain level. The gems also appear in different colours, which are more special and rare than the regular gems. In Crash Twinsanity there are 6 Gems hidden in each level for Crash to collect which count towards 100% completion.

Overview
The gems appear in every main Crash Bandicoot console game to date. They are typically collected in every level that contains a Power Crystal. The gems are different from Power Crystals though. Crash is forced to collect the Power Crystals in every level in order to advance in the game and plot, but gems are more optional for him to collect. However, they are still required to collect if the player wants to reach 100% completion.

Clear Gems
The most common way to collect gems is by breaking all the crates in a specific level. This requires Crash to go out and search every route and complete every Bonus Round to ensure that he earns the gem at the end of every level. There is also different methods to collect the normal gems though like completing a death route, completing a specific task, or by completing a secret level.

Colour Gems
Colour gems are similar to the regular gems, but function differently and are more rare. There is only one of each color gem in every Crash Bandicoot game and the common colours include blue, red, green, purple and yellow. The color gems usually require a different and more difficult task to obtain. Most often this is beating a challenging death route, but it also can be scouting a secret area of the level, or completing a special task for a certain level. Once a colour gem is obtained, it is counted towards the regular gem total. The difference between the colour and regular gems though is that the gems provide a special lift in certain levels once they are obtained. These special gem lifts allow Crash to access different areas in a level in order to break more boxes he couldn't break earlier, or take him to a completely different route to collect more normal gems. These gem lifts will only work once the color gem has been collected though. Otherwise, only an outline of the lift will appear if the gem has not been collected yet. In Crash Bandicoot: Wrath of Cortex, In any level that has a coloured gem, the secret path to it will become outlined if the player has died anywhere but the special areas.

What follows is a list of each kind of Gem and where they can be found in the first 4 Crash Bandicoot games from the main series.

Trivia

 * Spyro also has a usage for gems. They act as Wumpa Fruit except if he collects 100 (in value) he does not get an extra life.