How do you get the extra bonus gems in crash bandicout?

In Crash Bandicoot, you can earn extra bonus gems by completing certain levels with 100% completion. This typically involves breaking all boxes, collecting all the Wumpa fruits, and finishing the level without dying. Additionally, in some games within the series, you can find hidden areas or complete specific challenges to unlock these bonus gems. Keep an eye out for secret paths and alternate routes that might lead to additional boxes and collectibles.