Blue gem

The Blue Gem, also known as Sapphire, is one of the Colored Gems that first appeared in Crash Bandicoot. It also appears in the later installments of the series as one of the five collectible Colored Gems. Like the other Colored Gems, the Blue Gem is usually collected by completing a certain task. Once it is recovered, the Blue Gem will activate a platform/s in certain levels, known as Gem Paths.

Crash Bandicoot
In the original game, the Blue Gem can be obtained by smashing all of the crates and without dying after the first checkpoint in Toxic Waste. Once collected, it will unlock the Gem Paths on the levels Rolling Stones, Cortex Power, and Jaws of Darkness. Out of all the Colored Gems in this game, the Blue Gem is used the most for completion of other levels in the game.

Crash Bandicoot 2: Cortex Strikes Back
The Blue Gem returns in the second game, the same shape as the first game, though like all the Colored Gems it has become opaque instead of translucent. It can be obtained in the very first level, Turtle Woods. Rather than breaking every box, it is acquired by not breaking a single box. If the Clear Gem has already been recovered, then if Crash breaks 'x' crates during the level, a box counter will appear at the end stating 'x/0' crates are broken, hinting towards the Blue Gem's true nature. It opens up the Blue Gem Path in Hang Eight and part of the Multicolor Gem Path in Spaced Out.

Crash Bandicoot 3: Warped
The Blue Gem returns for the third installment, retaining the new look it got from the previous installment. It can be obtained by completing the Death Route in Tomb Wader from the fourth warp room. It opens up the Blue Gem Path in Sphynxinator and part of the Multicolor Gem Path in Bug Lite.

Crash Team Racing
The Blue Gem also appears in this racing spin-off installment. If the player completes the CTR Challenges on the race tracks Sewer Speedway, Tiger Temple, Dragon Mines and N. Gin Labs, to collect all Blue CTR Tokens, then the Blue Gem Cup will be available to play, where the four races can be raced again in a tournament. If the player wins the most points from all four races, they win the Blue Gem. It is required to complete the game because the other four gems are needed to unlock Turbo Track. The Blue Gem also unlocks Komodo Joe for the player to play as.

Crash Bandicoot: The Wrath Of Cortex
The Blue Gem returns for this installment and receives a slightly different sprite; it is a little less flat and a lighter shade of blue. It can be obtained by completing the Death Route in Arctic Antics. It opens up the Blue Gem Route in Tsunami.

Crash Bandicoot: The Huge Adventure
The Blue Gem returns here with a sprite identical to the Clear Gem, only a dark blue. It is hidden in Ruined. The move Death Tornado Spin is required to obtain it; Crash must jump from on top of the nitro switch crate back to the left reach it on a small hidden path in mid-air.

Crash Bandicoot 2: N-Tranced
The Blue Gem returns in this game, however for a different purpose then Gem Paths. In this game, there are Blue Gem Shards, found in the levels Tiki Torture, Magma Mania, Mister Lava Lava, and Eruption Disruption. The Blue Gem Shards used to unlock the level Fire Walker. In Fire Walker there is no crystal as it is replaced by a Blue Gem.

Crash Nitro Kart
Like CTR, the Blue Gem is used as part of the Blue Gem Cup where completing the CNK Challenges where the player must earn points by racing on Barin Ruins, Clockwork Wumpa and Electron Avenue. Upon completion, Polar can be unlocked.

Trivia

 * In Crash 1-3, the Blue Gem is always located in a level whose name is two words long for which the first word starts with 'T' and the second word starts with 'W': Toxic Waste, Turtle Woods and Tomb Wader.