How many oxygen atoms are in 1.90 g of quartz?
Do the hardness test. If you don't care if either gets scratched, scratch one with the other. The one that gets scratched by the other is the quartz, because diamonds are harder than quartz.
A diamond is much heavier. Also quartz has double refraction where diamond is single refractive. If you put quartz up to your eye and look through it you will see two of everything. Diamond does not double. The luster on diamond is much higher than the luster on quartz. If you have a refractometer you can easily get an Refractive Index on Quartz which is 1.45. The RI for Diamond is 2.42 which is higher than what the refractometer can read. Good Luck!
