Your answer depends on what you consider 'fine' or 'finest': colour, clarity, carat weight or cut or which of these in what kind of combination.
The diamond would be either D colour on the colourless scale, or a Fancy Intense Vivid colour if a coloured stone; internally it would be Flawless; it would have the heaviest carat weight possible for the quality and style of the cut.
Your choice.
The largest natural diamond found to date weighed more than 3,000 carats, and fit into the palm of a grown man's hand.
You can review the list, below, of named diamonds, none with the exact carat weight you describe, and documentation of the fact that a 99 carat diamond is not quite the world's largest.
'Rare' used to describe a natural diamond describes many diamonds. Red is generally acknowledged as the most rare natural colour in diamonds. Then, the Moussaieff Red, could be called the world's rarest diamond. You can read more about this stone, below.
Since most large and valuable diamonds known today were either gifts to royalty or spoils of war -- meaning no money traded hands in exchange for the diamonds, whichever of these you choose as biggest...flawlesscolouredraw diamondwhite...is priceless.
The Hope Diamond is a blue diamond.
INDIA .......................
Kentucky
tanzania
Kentucky
many organizations i have seen little boy scouts selling world's finest chocolate ( hint hint)
Wikipedia lists its colour as "finest white."
the red diamond
Mother Nature made the world's biggest diamond.
The worlds strongest rock is diamond
'Finest' is a matter of judgement. You should buy the man-made diamond that you can afford for the purpose you require. Read more, below.
The Smith mountain quarries in Arkansas are famous for producing the worlds finest sharpening stones.
they have one of the worlds finest hairs so they kill them but they don't know the law about that.