Board Thread:Questions and Answers/@comment-7657843-20161018162435/@comment-27020644-20161023221138

Alexj98 wrote: i can agree with that  i still think it could be the soul stone

on heimdall he did not change his armor the bits at the front have just been removed i would say to give asgardians more hope becuse of the tree on his armor Yea, it still could be the Soul Stone.

And I guess I didn't explain the patriotic meaning.

If you remember in Thor, when Thor drew the map of the Nine Realms, he outlined the planets with Yggdrasil, the tree that is also featured on Heimdall's armor. And I noticed that where Heimdall's gem is, is where Asgard is on the map of the Nine Realms.

So the gem symbolizes he is Asgardian.