In the Commedia dell’arte, Harlequin is characterized by his distinctive chequered costume. His role is that of a light-hearted and nimble servant. He pursues his love interest, Colombina, with wit and resourcefulness.
The ladder is an emblem of the aspirations of love, each step representing a
different stage in the course of falling in love.
See pg 76 of ‘The Triumph of Love’ by Geoffrey Munn (Thames and Hudson, 1993) for another Giuliano jewel based around a golden ladder.