Corrected entry: The "Infinity Stone" inside the orb is revealed as Tivan the "Collector" recounts its origin, before this moment no one knew the stone is inside the orb and no one can know afterwards, since Gamora sealed the orb. However during the pod pursuit Nebula says "The stone is in the furthest pod", the stone's existence is impossibly revealed. (01:02:00)
Phaneron
30th Dec 2014
Correction: Nebula is a daughter of Thanos and she is probably well aware that he is looking for the Infinity Stones, even if Ronan is not aware.
Phaneron ★