  If quarks are composite particles, then excited states are expected to play a
r\^ole in the Large Hadron Collider phenomena. Concentrating on virtual
effects, and using a large part of the CMS detection criteria, we present here
a realistic examination of their effect in diphoton production at the LHC. For
various luminosities, we present the 99 % confidence limit (CL) achievable in
$\Lambda-M_{q*}$ parameter space where $\Lambda$ is the compositeness scale and
M_{q^*} the mass of the state. For a q^* of mass 0.5 TeV, $\Lambda \leq 1.55
(2.95)$ can be excluded at 99% CL with 30 (200)${\rm fb}^{-1}$ integrated
luminosity.
