Glass tile is in most cases transparent, some colours more then others.
White thinset is the usual choice. But comes in varying degrees of sticky power.
Even if you buy your tile at home depot, I would not buy the thinset there.
Go to a real tile store, they will know what you need and have it.
HD will only have standard in white.
Will be different brands and names ... just ask at your tile store.
I have stuck 12"x12" ceramic tiles on the ceiling with this stuff, If you get some on your hands and you will.
Will be there for 2 weeks, stuff is like iron. Hard to keep it off your hands while working with it, the sooner you wash them before it sets up, better off you are.