Girolamo II Amati, born Hieronymus Amato on 26 February 1649 in Cremona, passed away on 21 February 1740 in the same city. He was an Italian luthier known for crafting violins and violoncellos, representing the fourth and final generation of the esteemed Amati family of Cremonese violin-makers. He was the son of the illustrious Nicolo Amati (1596–1684), the grandson of Girolamo Amati (1561–1630), and the great-grandson of Andrea Amati (ca. 1505–1577). There is limited information regarding Girolamo II's specific contributions as a luthier, with scholarly opinions varying greatly; some laud him as his father's most underrated pupil, while others argue that his instruments fell short of the high standards set by his predecessors. There are also suggestions that Girolamo II primarily managed the Casa Amati workshop rather than actively participating in the crafting process. Variations of his name include Hieronymus II, Girolamo II, Gerolamo II, Ieronimo, Jerome, Hieronimo, Hieronimus, and Hieronymus Amatus.

Girolamo II's father married late in life, at the age of 49, to Lucretia Pagliari (ca. 1619/21–1703), with whom he had nine children. Girolamo II, the third child, became the heir to Casa Amati after the early death of the firstborn, Girolamo Francesco Amati (1646–48). He began his apprenticeship under Nicolo Amati at a young age, around 7 or 8 years old, alongside Nicolo's most talented student, the future patriarch of the "Guarnerius" dynasty, Andrea Guarneri (1626–1698), who was 15 at the time. During the years 1641 to 1657, several other notable students, including Francesco Ruggeri (ca. 1628–1698), Giovanni Battista Rogeri (ca. 1642–ca. 1710), and the famed Antonio Stradivari (1644–1737), also learned at Casa Amati's workshop. Girolamo II likely began assisting in the workshop as early as 1660, when he was only eleven years old, driven by the high demand for skilled luthiers. In 1678, he married Angela Carettoni (16??–June 1685), who died seven years later. They had three children: Victoria Aloisia (b. July 1679–??), Eufrasia Scolastica (b. Nov 1681–??), and a son, Nicola Giuseppe Marie Amati (13 May 1684 – bur. 26 July 1687), who did not survive to adulthood. The fates of Girolamo's daughters remain unknown, and he did not remarry after his wife's death.

In 1684, at the age of 35, Girolamo II inherited Casa Amati following the death of his father, taking over the distinguished workshop. By this time, the competition in Cremona had intensified, as the demand for Cremonese violins grew across Europe and beyond, largely due to the legacy of his father and the many makers who had been inspired by the Amati family, particularly through the renowned "Grand Pattern." The reputation of the Amati name presented both opportunities and challenges for Girolamo II, as he faced scrutiny and comparison to the celebrated instruments of his forebears and the rising Casa Stradivari. His situation mirrored that of Giuseppe filius Andreæ Guarneri (1666–ca. 1739), who also encountered significant difficulties in maintaining the family legacy amidst Stradivari's success.

In 1697, Girolamo II moved to Piacenza due to unspecified legal issues. His activities during the following two decades are largely undocumented, and it is believed he may have retired from luthiery. Instruments attributed to him from 1703 to 1723 have been misattributed in literature to G.B. Rogeri of Brescia or Giuseppe Sneider (fl. ca. 1690–1725) from Pavia. Around 1715, he returned to Cremona, where he lived until his death at the age of 91.

Labels: - He continued to use Girolamo Amati's labels: * "Hieronimus Amati Cremonensis Fecit Anno Salutis 16__" - A handwritten inscription found inside an "old Amati violin" (presumed to be from Nicolo Amati) in 1806 by the Mantegazza brothers in Milan reads: * "Revisto e corretto da me Girolamo, figlio di Niccolò Amati, Cremona, 1710" ("Revised and corrected by me Girolamo, son of Nicolò Amati, Cremona, 1710")

- Presumably authentic labels include: * "Hieronymus Amati, figlio di Niccolo Amati Cremona 17__"

- Variations noted by Cecie Steiner include: * "Hieronimus Amatus, fecit Cremonae, 1670" * "Hieronimus Amatus Cremonensis, fecit anno salutis, 1697" * "Hieronymus Amatus, Cremonen, Nicolai fil., 17—" * "Hieronymus Amatus, Cremonensis, an. 1700"