As well as the Clear Gems that will be collected along your journey to defeat Dr. Cortex in the original Crash Bandicoot, you will also need to recover magical gemstones known as the Coloured Gems. They are six of them in total and can be collected by breaking all the boxes in the level where the gem resides.
Unlike the other games in the trilogy, you will need to complete this task without losing a single life. If the area in question includes a Tawna or N. Brio bonus round, failing it will not count towards your death total.
Here are all the locations for each of the coloured gems you can find in Crash Bandicoot as part of the Crash Bandicoot N’Sane Trilogy. This guide also works for the PS1 version of the first game in the trilogy, in case you decide to replay the original game.
Location: The Lost City / Hog Wild (If playing the original Japanese PlayStation version of the game.)
Location: Toxic Waste
Location: The Lab
Location: Generator Room
Location: Lights Out
Location: Slippery Climb / The Lost City (If playing the original Japanese PlayStation version of the game.)