Buying coins, bullion, and currency slabbed from third party graders: NGC, PGCS, ANACS, and ICG authenticates the honesty of what you are buying. The authenticity of the coin vs couterfiet eases the investor's purchase. 

Grades are in the eyes of the grader in each of the companies and often represents differences between values from one grade to another.

These slabs will preserve the item for long term for archival storage.