Information:

Vert de Mer is an Italian Marble, hence its name:   Vert = Green   &   Mer = Sea.
It originates in Genoa - a commercial city in North West Italy in The Gulf of Genoa.

It consists of metamorphic limestone with green elements which give Vert de Mer its 'Green Sea' appearance.
The formation consists of various tones of rich translucent green which include near-white veins set on a black background.
It is used on small ornaments, clocks etc. through to large decorative marble columns and wall panels.

The painted imitation of marble; 'marbling' is taught at various places throughout the world.
See:   http://www.painting-effects.co.uk/workshops.htm