In Avengers: Age of Ultron, we are aware that the Vision's body (the Vibranium-infused body Ultron had created) had the Mind Stone embedded in it and wielded the stone. We also know that Ultron had broken apart the gem in Loki's scepter to get the Mind Stone (the yellow Infinity Stone).
My question is thus: How did Ultron know the Scepter had an Infinity Stone in it? It wasn't clear to me how he learned of the Stone inside the Scepter so how did he learn it existed?