  We propose the enhancement of $\Lambda_c$ yield in heavy ion collisions at
RHIC and LHC as a novel signal for the existence of diquarks in the strongly
coupled quark-gluon plasma produced in these collisions as well as in the
$\Lambda_c$. Assuming that stable bound diquarks can exist in the quark-gluon
plasma, we argue that the yield of $\Lambda_c$ would be increased by two-body
collisions between $ud$ diquarks and $c$ quarks, in addition to normal
three-body collisions among $u$, $d$ and $c$ quarks. A quantitative study of
this effect based on the coalescence model shows that including the
contribution of diquarks to $\Lambda_c$ production indeed leads to a
substantial enhancement of the $\Lambda_c/D$ ratio in heavy ion collisions.
