They were not very specific about all the things Rose did over her life, one of them being raising horses, which in reality is a sure fire way to loose significant sums of money, the only way you could do that is to be subsidize by someone. The writers smartly wrote the raising horses dream in as it is a common fantasy.
The elderly Rose travels with an enormous sum of luggage, an amount only someone who was extremely rich could possibly be accustomed to doing. Yet she lived a lifestyle that ensures rapid wealth reduction unless she was really good at bagging very rich men, something the movie points out she is on an all out effort to avoid. To pack her luggage she would need at least three servants plus her long suffering granddaughter and a U-Haul truck just to get that amount of luggage to the airport. Especially on short notice.
The Rose character has an annoying I'm so independent yet live in a way which requires an army of servants, not to mention the financial requirements for that, because I am better than everyone else mindset. I am always right, I can do whatever I want with no consequence, am the center of attention, and most importantly not required to provide anything financially to anyone and yet everyone else will support me without question. As Rose I have always had a large sum of wealth yet have never had to pay anyone anything, they all support me no matter what I do or what I engage in. I am so good I can through all this wealth away, it does not mean anything because I'm so good. Reality, I am the cheapest creature on earth. I know it is a common very appealing fantasy, if not over the top on selfishness.
Rose could have taken a que from the American tradition started by 19th 20th and even 21st century super wealthy. I am thinking of the Rockefeller not be understated a whole very long list of others who gave there wealth away for a wide varsity of philanthropic causes
If Rose did give the diamond to some worthy cause she would have been a saint albeit living a lifestyle far beyond her means without a benefactor.