Precious Natural stones or Gem Stones history seems centuries old, we see it in egyptian kings palances, we see it Mughal empires of India, and Turkish old empires and in crowns of English royal family. Maily it's relation is with beauty in rareness, certain people believe in their healing effects over human body , sprituraly. May be belevers think about stars of luck.
Some common clues of natural precious stones are their colors which are long lasting colors while we see all others colors which are artificial, are just for few years, they gradually damn with passage of time, and natural stones colors are evergreen and everlasing, Three main colors , Red , Green, and Blue. in these colors stones are very precious, we see ruby, that keeps much cost, we see saphire, which keep cost, and we see emerald in green , very costly.

Stones valuation is depand over the scaling , mostly 4Cs, mean their calarity, their cut, their caret (weight) and their color. Ususaly Calrity, of stones depends much valuation. flawless, Very very slight inclusion(VVS) stones are very valueabel, some collectors have loups of 20x,
stones valuation is good above 5 cts. but precious stones like ruby,diamond etc. is anyhow keep much cost even below of 5cts.
Origin of precious stones are Burma, Srilanka, Pakistan, India, Afghanista. Tajikistan.
If we talk about blue saphire, best are of Kashmir, then Srilanka. Pakistan is famous for Emerald, Ruby , Peridot, Aqua, and Sapphire. Diaonds are mine in India too. Stones valuation is infact for their hardness, and Diamond is on top in hardness of stones, then ruby and saphire and emerald. Opal , the fire of red, blue and green is mined in Australia and Ethopia(Africa).