Just opened my first Blu-ray title why isn't the disk blue on the bottom?

Deja vu. Why do I feel like I've read this before?

I thought you were funny !
Though at least use Indigo or Violet light since they have higher frequencies and shorter wave length. Green falls between red and blue. Don't you know your physics man

they are the exact same gray color that HD DVD i think..

I thought it was the PS1 discs in black.

What a waste of thread.

Early PS2 games came on blue CDs. When all the games started coming on DVDs this process was abandoned.

There were and are a few of the infamous blue PS2 CD games out there which were released many years later into the PS2's long lifetime. These include Contra: Shattered Soldier and LEGO Star Wars. They are infamous because many PS2s were unable to read the blue PS2 CDs, especially the earlier ones which were also prone to the infamous disk read errors.