This marble originates from the region of La Spezia in the north of Italy.
It is a black marble filled with veins bended repeatedly all going in a parallel direction, also known as ‘chains’.
The colour of the veins varies from golden yellow to sometimes even white (the marble is then also called Portargent) and determines the value.
Portor with a deep black background and golden veins is the most beautiful and therefore the most expensive.