@Alexlayer  
Those are good interpretations. I always felt there have been three classes of Cutie Marks. One being the standards that you would see on most every other pony like flowers, fruit, or other every day items. The second tier would be the mixed ones like what you see on the CMC’s, theirs are not that common but we do sometimes see uncommon marks in the series. Specialist in their fields. And in an ever changing world. New marks will appear.
 
Lastly we see the very special ones. Like what Twilight and Shimmer have. These have very deep meaning or a connection to some great force in magic like you suggested. Of course the differences in the second and third tier CM’s could be very fine and almost indifferent to each other.
 
In any case… Nice her mark makes the best Tattoo for the fact it has many interpretations. ³

@Josh103  

 
Well, symbolism wise, in terms of design, it’s clearly meant to evoke the Yin-Yang symbol, and the fact that it’s a sun is probably meant to suggest a connection with Celestia. I do wish we’d get an in-universe explanation on how it represents her “Special Talent”, though. Then again, it might be that astral figures like stars - much like Twilight - are often just an iconic representation of “Talented with Magic” in Equestria.
 
Some fanfiction interpretations I’ve seen either have it that she’s particularly skilled with Fire Magic, or in one instance I particularly liked, to “Bring out the best out of something or someone by shining a light over them”, which Sunset had originally interpreted wrongly, thinking that “something or someone” was meant to be just herself, in turn leading her to her downfall until she learned better.

Always loved Sunset’s cutie mark. Wonder what it could mean.