Hiding with magic!

[Renen]

Can I use consealing amphora (or greater version of it) power, to hide because it grants concealment?

[Zaq]

As long as you're not being observed, I believe that you can use Hide with whatever concealment you have handy. If you are being observed, I don't think non-total concealment is sufficient, barring HiPS of some kind.

[Renen]

Gm thinks that because amphora has some fluff that says its sparkly or something, prevents me from hiding with it

[Curmudgeon]

Actually, your DM is probably thinking about this limitation of the power:
Using concealing amorpha, you weave a quasi-real membrane around yourself. You remain visible within the translucent, amorphous enclosure. If you remain visible, you're not hiding. Greater Concealing Amorpha grants total concealment, however, so you don't need to (aren't allowed to) Hide.
You need cover or concealment in order to attempt a Hide check. Total cover or total concealment usually (but not always; see Special, below) obviates the need for a Hide check, since nothing can see you anyway.

[Lightlawbliss]

Gm thinks that because amphora has some fluff that says its sparkly or something, prevents me from hiding with it

you can hide just fine, but DM would be perfectly justified saying the stuff hiding you isn't hidden.