Hyacinth was a martyr of Amastris, a coastal city of Paphlagonia on the Black Sea in Asia Minor, commemorated on July 18. According to the synaxarion he was born to pious Christian parents, named in the Greek tradition as Theokletos and Theonilla, during the episcopate of Bishop Herakleides of Amastris. The tradition relates that an angel appeared and gave the child his name.
The accounts preserve a story from his early childhood: at the age of three he is said to have prayed for a dead infant, who was restored to life, after which the two children grew up together leading an ascetic manner of life. As a young man he was moved by zeal against pagan worship. Noticing that the pagans of the city venerated a tree — described in the Greek synaxarion as a hollow elm — he cut it down, an act that led directly to his arrest.
By tradition he was seized by the governor, named in the sources as Castritus (Canstrisius), together with other notables of the city, and subjected to severe tortures: he was beaten, all his teeth were knocked out, and he was bound with ropes and dragged along the ground outside the city. He was then cast into prison, where, after much suffering, he died and gave up his soul to God. The sources do not record a precise year, though his era is placed among the early, pre-Nicene persecutions.