Tuberous Begonia in Tempered Glass

I decided to try another tempered glass mosaic. This is a photo of a tuberous Begonia grown by Paul Carlisle, famous tuberous grower. I glued the photo to the substrate and then used Mac glue to affix the tempered glass pieces. I find epoxy is just so messy so I tried this method instead. So far, so good. Today I plan to grout though I have no idea what color to use. Maybe charcoal.

And below is a picture taken last weekend of a real tuberous Begonia grown by Paul Carlisle. Maybe I should use this photo instead.

It's going to be hot here in Santa Barbara today (78°) so I may not get to grouting. I like to grout outside to keep the mess under control.