These tiles are copper tiles and they were nailed onto a 3/4" plywood board. What I would do with glass tiles is use white thinset to set it onto a 3/4" plywood board. In order for the thinset not to distort the picture you need to apply the thinset and smooth it (not combed) before laying the tile on it..

Thanks so much for the answer! One thing I neglected to say was these tiles cost $28,000.00 ten years ago. Does that sway your answer? They were originally hung from a ceiling in Paris. They, I believe, could also be displayed on a large wall. The entire piece is around 9' x 12'.

Ok. Yes it would change my answer. Message me via Houzz and I will explain to you how it should be done.

How do I message you? Shall I call the phone number listed?

You can message me by clicking on the large green button on the top right corner of the page that says "contact me".