  Type Ib and Ic supernovae (SNe Ib/Ic) originate from hydrogen-deficient
massive star progenitors, of which the exact properties are still much debated.
Using the SN data in the literature, we investigate the optical $B-V$ color of
SNe Ib/Ic at the $V-$band peak and show that SNe Ib are systematically bluer
than SNe Ic. We construct SN models from helium-rich and helium-poor
progenitors of various masses using the radiation hydrodynamics code STELLA and
discuss how the $B-V$ color at the $V-$band peak is affected by $^{56}$Ni to
ejecta mass ratios, $^{56}$Ni mixing and presence/absence of the helium
envelope. We argue that the dichotomy in the amounts of helium in the
progenitors plays the primary role in making the observed systematic color
difference at the optical peak, in favor of the most commonly invoked SN
scenario that SNe Ib and SNe Ic progenitors are helium-rich and helium-poor,
respectively.
