Rubies Emeralds Topazs Onyxs Amethysts Diamonds Sapphire Amber Tanzanite
Mainly minerals and precious and semi-precious gemstones.
Because they're beautiful and/or rare.
Peter C. Keller has written: 'Gemstones of east Africa' -- subject(s): Precious stones 'Gemstones and their origins' -- subject(s): Precious stones
It depends. All gemstones other than pearls and opals are crystals, but most crystals are not gemstones.
The exact number of precious gems in the world is difficult to determine, as it depends on how one defines "precious." Traditionally, the most recognized precious gems include diamonds, rubies, sapphires, and emeralds. However, there are many other gemstones classified as semi-precious, and new gemstones are continually being discovered. Overall, the number of different types of gemstones is in the hundreds, encompassing a wide variety of colors and qualities.
The weight of precious stones is measured in carats. One carat is equivalent to 200 milligrams. This unit is commonly used in the gemstones and jewelry industry to indicate the size and value of gemstones.
1 pound of anything except some gemstones and precious metals = 16 ounces of it 5 pound of anything except some gemstones and precious metals = 80 ounces of it
All precious stones come from rocks, but pearls are formed by oysters. Synthetic gemstones are made in factories.
When describing them, you could call them precious gems or gemstones.
The precious and the semi-precious jewels and the gemstones were the major goods often brought to Persia by means of the Silk Route.
Fluorite is not particularly durable nor particularly rare as most precious gemstones are.
Carats is the measure of weighting gemstones 1 carat = 200 Milligrams 5 carats = 1 gram Hope this helps Ahmed