Emeralds provides you with a better chance of finding magical items when inserted into helms and gives you Dexterity when socketed in other equipment. Amethysts give you +% HP when socketed into helms and Vitality when inserted in other equipment. According to the Diablo 3 Official website, there are only 4 types of gems available at this time: amethysts, emeralds, rubies, and topazes.
Gems can be socketed into weapons and armor to boost specific stats based on the gem's color. If you are unfamiliar with Diablo 3 gems here are some of the things you need to know.
Today we'll take a look at Diablo 3 gem system. Gem crafting in Diablo 3 turned out to be something very sophisticated and interesting at the same time, something much more complex than it seemed at first glance.