Question

where are the hard stones found ?​

Answer 1

Diamond is the hardest natural material in the world. However, it's also brittle.

Answer 2

Answer:

Most gemstones form in the Earth's crust, approximately 3 to 25 miles beneath the Earth's surface. Two gemstones, diamonds and peridot, are found much deeper in the Earth. Diamond forms in “kimberlite pipes” that originate in the Earth's mantle (>125 miles) and end at the surface.