This technology includes the use of nanodiamonds to achieve background-free imaging. We present several techniques to reduce or eliminate background florescence by exploiting properties of the fluorescent nanodiamonds. In particular, magnetic field modulation of the fluorescence intensity offers a simple, robust, and easily adaptable method to obtain background free imaging in a variety of imaging modalities, i.e., fluorescence microscopy and wide field fluorescence animal imaging. The product would consist of a means of modulating a magnetic field in an imaging system combined with the fluorescent nanodiamonds that are the source of the fluorescence. In principle this technique could be adapted for use in wide field and confocal imaging systems. Importantly, this technique makes use of conventional continuous wave illumination.