What a beautiful dream! We don't realize how the other dimensions (including even the Heavenly dimensions) incorporate gemstones in thier cities and living areas. This may be why when I leave gemstones out in the faery's garden, they are always missing– even though noone goes near that garden and there is a fence blocking the neighbors from access. I will post more about that on another thread.
To get back to your dream– sounds to me that this was definitely a real memory you had from the past- and this was NOT your "imagination". People often blame everything on a vivid imagination, but there is no way you could have concocted all of that up unless you saw a movie of the same Beings in it–and same obelisk, etc.. –which I doubt.
It MAY have been a scene from your past life before you were incarnated human, but it also could have been an Empath dream– where you picked up on a past account that happened centuries ago and you actually felt everything that elven girl with the black long hair was feeling– you took part in her experience with her parents. Maybe you even knew her as a good friend. When you hear some mention becoming united with someone else- becoming One- it actually means being united with someone in spirit– where you feel their pain, feel their joy.
I would treasure this beautiful dream- and while you may not mentally understand all of it on this side of the viel, one day all will be made clear regarding it :-)
Thankfully, our lives still continue on after we leave this body
love
Lisa Grey Eyes