Ni2+(aqueous) + 6NH3(aq) ---> [Ni(NH3)6]^2+ (aq)

The Ni2+ ion is green, but the addition of the strong ligand, NH3, turns the solution blue.

Strong ligands absorb light at higher energies like the color blue, so they reflect red and appear red in color. Why does the strong ligand, NH3, act like a weak ligand and present as blue in the final product of [Ni(NH3)6]2+?