Turns out that the quantum Zeno effect has been observed in diamond.
The researchers focused on nitrogen–vacancy (NV) centres, imperfections in diamond that arise where an atom of nitrogen and an empty space replace carbon atoms at two neighbouring spots in the crystal lattice. The team used microwaves to change the magnetic spin state of an electron located at an NV centre, and then used a laser beam to trigger red fluorescence that revealed which of two possible states the electron was in at any given moment. When they measured the NV centre in this way, the researchers found that the oscillation between the two states was disrupted — just as would be expected if the quantum Zeno effect were operating.
The paper is to be published in PRA, but the preprint is online.