Other imitations include: white sapphire, yttrium aluminum garnet (Y.A.G.), colorless spinel, colorless rutile, and strontium titanate. These are even easier to reject as diamond, due to their clearly different appearance in comparison. White sapphire shows weak double refraction, so the absence of dispersion should be quite apparent. Y.A.G., spinel, rutile, G.G.G., and strontium titanate, are very soft compared to diamond, so the rounded facet edges should be quite obvious under 10x.

If your interest lies in the identification of other gemstones (including the ones just listed), some additional lab equipment would be a good idea, including a refractometer, a spectroscope, and heavy liquids for measuring specific gravity.