MrsE88,
Absoliutely! I asked about this a few weeks ago; somewhere online there's a pic of a huge discuss tank with an aqua to white fade background that makes it look like you're (observer) snorkelling in a pond - the tank's maybe 3' front to back, but the fade makes it look/feel like acreage.
I'm doing an in-wall now that'll be 3' tall but only 17" wide, so it needs that feeling of space/depth. I'm trying to find that image (and/or advice) as I don't remember if it faded top-to-bottom or bottom-to-top.
In my case colours/shades will (theoretically) be pigments within the sealing epoxy layering. It'll be a gentle or possible line-layered fade rather than a sponge/paint effect, though this does sound interesting...