Every art discipline has its own «language», a specific proprietary semantic.
When an artwork, that has been executed in other art forms, must be interpreted in Mosaic Language, it must undergo a simplification in its patterns and areas of colour.
In painting, colour is obtained by mixing other colours. The mosaic artist uses matter that is more rigid, and hues can be obtained by placing bits of coloured matter next to one another.
A possible alternative is grinding and reassembling.
Stone can be recomposed; glass enamel can be melted to make new colours.
But this is a different story…