Blue gem

The Blue Gem is a rare type of gem in the Crash Bandicoot series. It's known to be a sapphire. Along with the other coloured gems this gem is very powerful and opens up secret areas.

Crash Bandicoot
In the original Crash game, where the colored gems were earned on the same way as the clear gems, the Blue Gem is obtained by breaking all the boxes in Toxic Waste. It opens up the Blue Gem Paths in |Jaws of Darkness, Rolling Stones and Cortex Power.

Crash Bandicoot 2: Cortex Strikes Back
The Blue Gem appears like a rather flat one. In this game it can be obtained in Turtle Woods by breaking no boxes. It opens up the Blue Gem Route in Hang Eight and part of the Multicolour Gem Route in Spaced Out.

Crash Bandicoot 3: Warped
The sprite of the Blue Gem is exactly the same as in Crash 2. It can be obtained by completing the Death Route in Tomb Wader. It opens up the Blue Gem Route in Sphynxinator and part of the Multicolour Gem Route in Bug Lite.

Crash Bandicoot: The Wrath Of Cortex
The Blue Gem gets a different sprite. The gem becomes more clear. It can be obtained by completing the Death Route in Arctic Antics. It opens up the Blue Gem Route in Tsunami.