At the end of Titanic, why does Rose throw away the necklace?

I wondered this myself when I first saw the movie, and it really bugged me — I just didn’t get it.
Rose didn’t seem to be a crazy old lady. Sicher, she had a good time – she became an actor, raised babies, flew planes, went on roller coasters, and rode horses “like a man” – all that might’ve addled her brain, and made her much less practical about these kinds of things than I’dve thunk, given her spunky streak. Ich meine, c’mon, she knows firsthand you can’t take it with you, und doch, she was trying. It seemed inconsistent with her character. I don’t know any old ladies who aren’t downright cheap, when it comes right down to it. Meine Mutter würde meine Kinder schicken $10 Schecks für ihre Geburtstage – Manchmal. Ernsthaft, Jetzt.
Also, Hier ist ein unbezahlbarer blauer Diamant, und sie wirft es über die Seite — Worum geht es?? Ihre Familie, wen sie möglicherweise jahrelang angelogen hat, sollte nicht von ihrer Geschichte profitieren? Schenken Sie einer Frau ein College oder so, weil ich laut geschrien habe! Die Überlebenden oder Familienangehörigen der Menschen, die auf der Titanic ums Leben kamen, sollte nicht profitieren? Oder vielleicht sogar Cals Erben, denen nichts mehr übrig blieb, als er sich danach selbst beleidigte 1929 Absturz, Sie sollten an den Sünden ihres Vaters festhalten? (schließlich, Cal hat ihr seinen Mantel gegeben, und die Halskette war in der Tasche – man könnte meinen, sie hätte ihm vergeben, inzwischen). Vielleicht wollte Rose all diese rechtlichen Erbschaftsstreitigkeiten und Streitigkeiten vermeiden; könnte so einfach sein.
Schlechter, obwohl, she’s letting Brock and other divers and would-be treasure-hunters have it. Practically, this doesn’t make that much sense; sooner or later Brock’s probably going to find it unless some big fish eats it first, and she’s gotta know that. Just because you make a grand gesture doesn’t mean someone’s not going to come along and clean it up after you, and sort of blow it, sooner or later. Consider architectural preservation battles, or how many art treasures have been lost or destroyed throughout history. Hanging gardens of Babylon? Library at Alexandria? All gone. And what about the pyramids? Treasure-hunters, or rather, tomb-robbers, persevere and don’t have a lot of respect for romance, except for its droppings. Thank goodness for curses! Thinking this through, Rose’s action is an unintentional bummer, and depressing comment on the naivete, and temporal nature of “eternal” Liebe.
Vielleicht.
And maybe she just was a crazy old lady – I know a lot of them, and aspire to be one myself one day (not this week, I hope), so why not. Sometimes it’s better not to think too much or overanalyze, especially when watching BIG pictures. It could be argued that old Rose’s action was selfish and self-absorbed; but I do believe that that’s exactly what Jack had made her promise to do, as he slips into the freezing waters – he makes her promise to live, selfishly and fully, without regard to structure or convention, and to “never let go” of that promise.
By looking at some fan sites, I discovered that there was an alternate ending proposed; Rose’s granddaughter and Brock try to stop Rose at the rail from tossing the necklace into the murky depths. Cameron cut the ending because supposedly he decided that it wouldn’t matter to an audience whether or not Brock got redemption. Apparently, Rose lets him hold the Heart of the Ocean, and then he gives it back to her; she then drops it in the water ceremoniously, Verständnis…something. I’m sure there would’ve been a shot of Brock, nodding ponderously, looking recalcitrant about his greed, and humbled by witnessing an eternal love (while keeping his fingers crossed that coordinates of the location were being recorded, for his next dive, once the old lady had had her nightcap and was all tucked in).
It’s much more romantic to simply surrender to the story, emotionally, despite that little voice that…wait, why didn’t Jack just knock off one of those dead people off a fridge and get out of the water, and live, zu? Oder…didn’t she care about her mom, at all? Oder…was he really THAT hot? He can’t have had good teeth. Really. Oder…Also, whatever.
Upon learning that there’s no record of Jack, überall, old Rose says: “NEIN, there wouldn’t be, would there?…A woman’s heart is a deep ocean of secrets. But now you know there was a man named Jack Dawson and that he saved me…in every way that a person can be saved. I don’t even have a picture of him. He exists now…only in my memory.”
Early in the film, Cal gives Rose the Heart of the Ocean, he says: “Open your heart to me Rose”. And she covers the diamond with her hand. At the end of the film, old Rose lets the Heart of the Ocean go, having opened her heart to Jack and his memory. She lets go, releasing Jack’s memory and her secrets, and letting go of her promise to him to live, because she knows her time is done. Rose’s heart, her Heart of the Ocean, her will to live, rejoins the deep ocean from whence it came.
Geez, now I’m getting all weepy.

