The time‐resolved photoconductive response of several natural and synthetic semiconducting (IIb) diamonds has been measured at room temperature using an optoelectronic cross‐correlation technique. The response times are between 100 and 300 ps, indicating a capture cross section for the photoexcited holes of ∼4×10−13cm−2. We have found that IIb diamonds can serve as a simple, rugged pulsed laser detector for 0.45<&lgr;<4.2 &mgr;m.