Ruby and sapphire; is there any difference? And what are the basic characters?

The name of Ruby is from Latin name "Ruber", which means red color. And the same as Sapphire, it is from "Sapphins", which means blue color. Both ruby and sapphire have the same scientific name as corundum, corundum has a variety of colors, besides the familiar red and blue, it also includes yellow, green, purple, pink, gray and transparent, etc. Ruby and sapphire are known as the "four kinds of precious gem" with diamond and emerald because of their magnificent and limpid, attractive color, high hardness and rarity. In another hand, ruby is a little more precious than sapphire, because ruby has more attractive color and rarer in quantity

In corundum family, the most representative or common gem should be ruby and sapphire, their chemical composition is alumina, Mohs hardness is 9; this hardness is just after diamond in natural mineral.

What is the emerald? And what is its basic character?

Emerald is one of the members in the Beryl family, as the extremely rare species; it is said that emerald can keep our eyes bright. The ancient Greeks called emerald to be " gleamy jewel." She is the represent of eternal life and the meaning of faith, what's more, the symbol of the natural beauty and harvest. Generally, people believe emerald can bring constancy strength to lovers. The main birthplace of emerald is in Colombia, Zambia Africa and Brazil.

The main chemical composition of emerald is Be3Al2[Si6O18], Mohs hardness is 7.7, the main color is bright green. In addition, emeralds is rather fragile, in case of collision it will be broken easily.

How do you evaluate the gem to be good or bad?

The standard of how to evaluate the gem to be good or bad is difficult to make. So far, there is still no effective evaluation standard about the quality of gem, today, the common viewpoint is just evaluate from the size, color and the blemish