An apparatus and method for imaging metallic nanoparticles is provided. Preferably, the invention provides for an apparatus and method for detection of gold colloid particles and for accurate reporting to the operator. The apparatus includes a substrate holder for holding the substrate, a processor and memory device, an imaging module, an illumination module, a power module, an input module, and an output module. The apparatus may have a stationary substrate holder and imaging module which are proximate to one another. The apparatus provided for a compact sized system without the need for complex motorized devices to move the camera across the substrate. Further, the apparatus and method provide for automatic detection of the spots/wells on the substrate, automatic quantification of the spots on the substrate, and automatic interpretation of the spots based on decision statistics.