Diana Runes explained
There's one set of runes for Diana on patch 14.12 that is the clear favorite for LoL players and pros alike. The best Diana rune paths on the position 
Mid are 
Sorcery as the primary path and Resolve as the secondary path with a pick rate of 58%. Besides picking runes on Diana you should learn how to play Diana and if you are interested in pro matches take a look on how a pro builds Diana. If you want to discuss 
Diana then you should visit the champion subreddit.
Diana runes from primary path
Sorcery empoweres abilities of Diana and increases the available champion resources. Most of high elo players – and our LoL pros in the the major regions – have agreed that Phase Rush is the best keystone rune to run on Diana. Phase Rush offers more flexibility and options to betake oneself in and out of danger, which can be helpful since that's essentially the main playstyle of Diana. Other primary runes on Diana are Manaflow Band, Transcendence and Scorch.
This is usually followed up by taking Manaflow Band for additional mana and mana regenaration. Transcendence for some more Ability Haste. Scorch increases your control in the early game.
Diana runes from secondary path
When it comes to your secondary path, most Diana players prefer to go with Resolve. Resolve empowers the survivability of Diana and increases the tankiness. On the Resolve path, the best runes for Diana are Bone Plating and Shield Bash.
Bone Plating make Diana overall tankier, by decreasing the amount of poke damage in the early game. Shield Bash powers up your tankiness and empowers your next basic attack while you have a shield.
FAQ for Diana Runes
Which is the best keystone rune on Diana?
The best keystone rune on Diana is Phase Rush. This Diana runes setup is then referred as Diana Phase Rush.
What runes does Diana use?
Runes from the paths Sorcery and Resolve are the most used runes on Diana. For the exact pick rates of Diana runes used, you have to study the rune distribution presented.