Bartolomeo Giuseppe Guarneri, better known as Giuseppe Guarneri del Gesù (often abbreviated as G. Guarneri del Gesù), was an Italian luthier from the prominent Guarneri family of violin makers. Although your query refers to Bartolomeo Giuseppe Chiari, there seems to be a mix-up; Chiari was an Italian painter active during the Baroque period, not a luthier. It appears you may be referring to Giuseppe Guarneri del Gesù, who was born in 1698 and died in 1744, and was among the most famous violin makers of his time.
If indeed you meant Giuseppe Guarneri del Gesù, here is his biography:
Giuseppe Guarneri del Gesù was born in 1698 in Cremona, Italy, into a family with a strong tradition of violin making. He was the grandson of Andrea Guarneri, the founder of the Casa Guarneri workshop, and the son of Giuseppe Giovanni Battista Guarneri, also a violin maker. Del Gesù's work is often compared to that of Antonio Stradivari, another legendary Cremonan luthier.
Del Gesù's violins are renowned for their powerful, rich tones and are favored by many professional musicians. He introduced several distinctive features that set his instruments apart from those of his contemporaries, including a flatter and broader design, as well as a thicker application of varnish. These characteristics contribute to the unique sound of his violins.
Throughout his career, del Gesù struggled with financial difficulties, and his life was marked by periods of intense work followed by intervals where he produced few instruments. Despite this, his violins have become some of the most highly prized and sought after by violinists and collectors worldwide.
Giuseppe Guarneri del Gesù died in 1744, leaving behind a legacy that has only grown with time. His instruments are considered masterpieces of craftsmanship and continue to be studied and revered by luthiers and musicians today.
