Final answer:
A polarizing microscope is the best choice to verify the presence of a gouty tophus in a sample unstained by methanamine silver, as it detects the birefringent monosodium urate crystals characteristic of gout.
Step-by-step explanation:
The presence of a gouty tophus, which is not stained by methanamine silver, could be verified using a polarizing microscope. This type of microscope utilizes polarized light to detect birefringent materials, such as the monosodium urate crystals typically found in gouty tophi. Unlike dyes and stains that can alter or damage samples, polarizing microscopy allows for the observation of these crystals in their native state, enhancing their visibility without the need for chemical modification.