A straightedge of wood or metal used to measure and mark straight reference lines on a marble block.
Riga is a straightedge used in block preparation and measurement. Le voci del marmo describes it as a wooden or metal tool used to mark and measure straight lines on the marble block.
Etymology
Italian riga, “line, rule, or straightedge.”
Sculptor Notes
A straight reference line can govern an entire operation: squaring a block, establishing a base, laying out saw cuts, or transferring model measurements.
References
https://levocidelmarmo.sns.it/scheda_oggetti_relazione.php?denom=riga&id=42