What are Gems?
You can upgrade your equipment in Call of Gods by embedding gems into them. At least one gem can be embedded into all equipment of grade blue and above. Each embedded gem will increase one of your hero's attributes.
Gems, like all items in Call of Gods, come in 5 ascending grades – White, Green, Blue, Purple and Orange with higher-graded gems giving higher attribute bonuses.
How do I get Gems?
The easiest way of obtaining gems is by purchasing them from the Shop. White, Green, Blue and Purple gems can be purchased at the Shop.

White and Green gems can be obtained by fighting monsters in the World map. You can also find White, Green, Blue and Purple gems by exploring Dungeons.
Orange gems are the most powerful gems in Call of Gods and can only be obtained by spinning the Wheel of Fortune. Other gems can also be obtained at the Wheel of Fortune. Below is a list of the Orange gems in Call of Gods:

How do I embed Gems into my equipment?
To embed gems, you need to visit a Gem Socketeer. There is a Gem Socketeer at Sanctaria (Ironforge), Arthlan (Ironbark Forge), Necrolis (Ironbone Forge) and Regia Deorum (Hall of the Fearless).

Click on "Socket Items" to proceed to the Item Socketing menu.

The item socketing menu shows all the equipment in your inventory that can be socketed. The Frenetic Helmet that I have selected in the screenshot above has one empty socket and one creatable socket. Clicking on the "Create Socket" button allows you to create a new socket in that item.
Blue equipment can only have 1 socket, Purple equipment can have 1-3 sockets and Orange equipment can have 2-4 sockets.
Click on the "Add Gem" button to select a gem from your inventory to embed into your gear.

Click on the "Change" button to select a different gem. Click on the "Remove" button to remove the gem.
Click on "Embed Gems" once you have confirmed your decision. You can also destroy gems that have already been embedded by clicking on the "Destroy Gem" button.

Call of Gods Skills Guide >>

Call of Gods Guide: Getting from Level 1 to Level 10 >> 

Call of Gods Guide: Quest >>

Call of Gods Guide: Combat System >>

Call of Gods Guide: Recruiting and Using Heroes >>