My piece of Pietra Dura from Pitti Mosaici

Each piece has been selected for the correct tonal variation

When we entered the Medici Chapel, around the walls were the coats of arms of all the city-states. These were done by the apprentices. This lion is see through - you can see the skeleton underneath. This is not true Pietra Dura, because it has alabaster and marble. In true Pietra Dura all the stones must be harder than 8 on the Moh's scale(quartz, feldspar) except the blue of which only Lapis Lazuli was available.

The Last Supper on the Altar - sunset, shadows...

Ken had a torch, and we noticed the reflection from the translucent grapes. As the torch is moved, the reflection from each grape moves as it would a normal grape. This means that under each grape is either a polished sphere (opel?) or the grapes themselves are a hemisphere with the flat side up.

This is a table top - polished perfectly flat.

A closeup. Notice the broken string of the harp, petrified wood, shadows, shadings of the flute and leaves.

In the flash reflection you can see the joints - yet they are impossible to see with the naked eye.

Just a coffee table with precious gem stones - perfectly flat.