I have not done it, but have seen it done locally here. I would imagine the cost is outrageous. The one we saw was backlit and was beautiful.

Do you want to use the onyx in the bath itself or as a countertop in a bathroom?

I'm not really sure, I was thinking of using it more decoratively. But I'm wondering how porous it is and how easily does it scratch or chip?

Thank you!

Well we have illuminated Onyx tub surrounds and I know the contractors do apply multiple layers of sealant because the onyx is quite porous. Have a look at this link http://www.houzz.com/photos/users/nuwoled for images to give you a few ideas of how onyx can be used in the bathroom.

If you want to backlight it we can help you www.nu-wo.com and have a look at www.stoneveneerusa.com for a more cost effective option over onyx