I can't think of what else the brooch might symbolize but we'll never really know--it could be something completely insignificant that we'd have no way of guessing.
Personally I don't think that's the case at all. Because it is a letter, I think it must symbolize somebody. Remember that Alix never wanted him to be called Albert Victor, neither really did Bertie. It was forced upon them. So I think she would never commemorate her Eddy with an AV brooch as well. The more I read about Alix and Eddy the more I feel she adored him much more than is normal for a mother. But that is a good thing. It was Queen Alexandra who commissioned that big stained glass portrait of Eddy as a saint. I found a big version of that, I'll put it into the Eddy thread later. As well as all her other mourning rituals, visiting his room, etc. Wearing a lot of amethysts rather than bright jewels, wearing mauve and ''mourning colours'' for years. Carrying on at George's coronation, supposedly acting depressed at his wedding. It seems she couldn't get Eddy out of her head. So it makes sense to me she wore this brooch for him. But you are right, I haven't seen her wear it other than in this photo shoot, however often it is hard to tell what she is wearing (jewellery that is) because it is blurry, or she had SO much of it on.
I found a high quality picture of Alix wearing the brooch:
Please click.
You can see it is made up of stones of a dark colour - rubies or amethysts maybe. With a crown on it symbolizing Eddy's role as future King, or just his Royal status. I wonder if it is still in the Royal Collection. I like it a lot.
