Continuing my Summer Knight reread, we get Harry's description of Elaine, and aside from the usual he mentions that she is wearing a pentacle necklace identical to his own... We know or rather Harry believes that his pentacle came from his mother, that she wore it. It is his main link to her through the first three books, he fingers it, he feels her when he fingers it.. It is very special, no where up through Skin Game is it mentioned that another wizard wears such a necklace, except for Elaine.
So where did she get hers? Did her mother give it to her? Harry doesn't explain how she came to have an identical pentacle necklace to his own. He doesn't say he gave it to her, indeed where would he get the money for it? He doesn't say her mother gave hers to her. He doesn't say that Justin gave it to her. He implies that the necklace is a symbol of the bond between them. However Elaine never indicates that her necklace holds as deep a meaning for her as his does for Harry.. So what is the deal here?
What if Harry had been lied to from the beginning? While it may have come from his mother, it isn't a keepsake type of thing. We know that supposedly there were two or we think two possible star borns, Harry and Elaine. Harry is confirmed to be one, the jury is still out on Elaine. What I am saying is suppose only star born baby candidates get the necklace? Then while true that his mother left him his, she never wore it and it merely indicates his status as a possible star born, the same goes for Elaine. In fact this may have been one of the ways Justin selected them out of the orphanages. It stands to reason that Harry and Elaine wouldn't be the only two kids with talent among the hundreds of orphans who needed adopting... If Justin knew about star born, he may also have known about the distinctive necklace only they wear.
One more point, once Harry is more or less confirmed to be a star born, he is gifted with the jewel to put in it with the road map of the Ways, why not before?