Atlas Blue Obsidian has a watery feel to it.  It allows words to flow easily due to helping you clarify your thoughts before you speak.
 
The dreamy quality of this stone is helpful in dreaming up new ideas or ways of doing things.  It stimulates visions during meditation and allows the scenes to flow through your conscious thought.
 
Available:  1 (lower left), 2 (upper left), 3 (lower right), and 4 (upper right).  The price is per stone.