How many buyers do you think there are for a single 500 carat diamond? It could take 40 years to get your asking price...if ever.
But chop it up, and you can get your asking price much more easily.
No so. There are lots of buyers out there, but they don't want little bitty -- they want huge ones. Ask Mr. Winston or Mr. Cartier. The Arabs are buying them up as fast as they can. They are portable wealth, easier to move around than gold. A couple of times a year I stroll through the Smithsonian Natural History museum and look at the Hope diamond. It is stunning. Take a look at the Queen's diamond chandelier earrings. Note they are shown actual size:
http://www.royalcollection.org.uk/egallery/object.asp?exhibition=RT2&object=200171&row=12
And check out these suckers. They originally belonged to George III.
http://www.dailymail.co.uk/news/article-470063/Camilla-dazzles-60th--Queens-diamonds.html