Answer;
-Gemstones
Gemstones are nonmetallic minerals that are valued for their beauty and rarity rather than their usefulness.
Step-by-step explanation;
-Most gemstones form in the Earth's crust; the top layer of the Earth, with a depth of 3 to 25 miles. Only two gemstone varieties, diamond and peridot, form in the Earth's mantle, which represents 80% of the Earth's volume.
-A few gemstones form in the mantle, but all gems are mined in the crust. A precious gemstone has beauty, durability, and rarity, whereas a semiprecious gemstone has only one or two of these qualities.