Which diamond has the highest carat of shine?

Answer 1

This question doesn't quite make sense. A carat is a measure of the weight of the diamond, and measures nothing else at all. One carat = 200 mg or 1/5 of a gram. By 'shine' you probably mean brilliance; this can be measured by the return of light from the diamond. Clarity and colour both mean what they say, and don't really affect brilliance, which depends entirely on the cut. The cut which gives the most brilliance is known as the ideal cut.

Answer 2

The largest diamond by carat weight is the Cullinan diamond, which weighed 3,106 carats in its rough state. It was eventually cut into multiple diamonds, with the largest cut being the Cullinan I or Great Star of Africa, which weighs 530.2 carats and is part of the British Crown Jewels.