“Rubies” have no value and are used only for development and testing. To get Ruby, you need to use the Chain Rider bot built into TON Surf (it can give out 100 “rubies” at once, but once). If you need more of these tokens, you should contact the initiative community members personally or contact the TON Surf support team directly.
Thus, DevNet provides a stable environment for application developers. If you need to switch to the mainnet, you have to enter the Surf settings: Settings -> Advanced settings -> Developer mode.