A jeweler needed two diamonds of exactly the same weight to make a ring. The first stone she selected weighed 0.642 carat, the second weighed 0.599 carat, and the third weighed 0.625 carat.

By how much did the heaviest stone outweigh the lightest?

0.043 carat
0.042 carat
0.041 carat
0.04 carat

Help please? can you explain how people does it also? thanks.