cbingham: In the QFG1 remake, it was red. In QFG4, it suddenly turns to blue, which you notice if you look in Bonehead's eyes closely enough. AGD Interactive noticed, as they made it obvious in their remake of "King's Quest 2" that they believed the gem to be blue (If you talk to the skull on the bottom enough times, it eventually will speak and it will be obvious that it's Bonehead. They even got the same voice actor. It blows my mind how AGD Interactive didn't get the original voice actors for Valanice, Alexander, Rosella, or Connor, but they got Bonehead's voice actor). But in Heroine's Quest, it turns red again (it's an Easter egg than can be found in Sigrun's shop).

Also now that I think about it, for Heroine's Quest, the eye message and the hand message suggest that the gem may be the "Space Quest" gem, when that gem was clearly green. It might not have been obvious in the original Space Quest 2 with the AGI graphics, but in "Space Quest 3," we see the gem and it's obviously green. We see that gem again in Infamous Adventure's remake of "Space Quest 2" and it's obviously green. The gem in Sigrun's shop is clearly red, so it makes no sense to me that they try to get us thinking it may be the Space Quest gem.