Rubies

Rubies are used in the Flashmarket on the portal, when certain events are running.

They work just like Webcoins, but for the Ruby market, which tends to have better items for sale.

Hope that helps

Also, you will notice that Ruby items are only in the shop on average 3 days a week, usually every Wednesday followed by a couple of different days.

I always look for the day I can refresh for free multiple times to try and max out the rewards for earning XP