Which country is known for the production of most of the world's commercial-quality peridot?

The United States is recognized for producing the majority of the world's commercial-quality peridot, particularly from the San Carlos Apache Reservation in Arizona. This region is famous for its vibrant and visually appealing gems that meet the standards required for commercial use. The peridot from this area is valued not just for its quality but also for its historical significance, as it has been sourced consistently over many years.

While Myanmar, Pakistan, and Australia do produce peridot, their contributions to the global market in terms of commercial-quality stones are comparatively smaller. Myanmar is known for its historical deposits, but much of the peridot mined there does not reach the same level of commercial quality as that from the U.S. Similarly, while Pakistan has notable mineral resources, it has not established a reputation comparable to that of the United States for high-quality peridot. Australia also produces peridot, but again, it does not dominate the commercial market like the United States does.

Therefore, the United States stands out as the leading source for commercial-quality peridot, making it the correct answer.