Smoky Topaz

and how can you tell them apart in the jewelry?

We are talking about two entirely different minerals. First quartz crystalline form. Quartz is silicon dioxide SiO2 (not a silicate!) - Smokey refers only to its color, which in this case, brown to almost black, which is produced by millions of years of exposure to background radiation in the rock mother. It is also produced artificially by setting clear quartz in a room of cobalt-60 radiation that does the job in one hour.
The properties of quartz are the following: -
Refractive index of 1.544 to 1.553
Density from 2.65 to 2.66
Hardness 7

Topaz. These aluminum silicate, Al2 (OH, F) 2SiO4 containing varying amounts of OH and F. The colors are varied, but it has never produced the dark brown Smokey Quartz. The term Smokey Topaz is actually a misnomer coined by members less honest trade jewelry for sale at low prices as a quartz lot more to people who can not understand the precious stones. It is a term which shall not be used.
Topaz constants are as follows: -
Refractive index of 1.607 to 1.619 to 1.629 to 1.637
SG 3.50 to 3.60
Hardness 8

To summarize, if you have a stone that is in shades of brown (may have a greenish-yellow) to nearly black, it is unlikely to be any form of topaz. Testing the refractive index is a surefire way to tell. Beware of hardness tests that topaz divides very easily. and you can destroy a strong stone. If it is not cheap its topaze believe me.

Ugly fish suggestion scratch test is good. Quartz is softer and can be removed just by Topaz - Quartz 7 Topaz 8. So having a little quartz and to see if you can scratch your stone. Topaz fractures very easily, if so be careful.

Topaz is much denser than quartz, should be about 3.5 g / cm ³ but not really much use to you if you do not have ways of measuring the volume and Mass or large pieces of topaz.

Good luck

Well from a mineralogical point of view, they are different from other world that they are aluminum silicates containing both. They have different crystal systems, hexagonal quartz and topaz is orthorhombic. And they are different silicate structures.

That said, there is another way of telling a hardness difference. Quartz will create electricity through the piezoelectric. custom Topaz. Although the hardness test is easier to do.

You could do a hardness test Moe's, but I do not remember which has a higher hardness and you probably do not want to match your jewelry. But ultimately?

Topaz is a gem. Quartz is a notch above the glass. Visually, it is difficult to make a difference, but if someone substitutes for quartz topaz, they will cheat.

Topaz is a hydrogenated or quartz-aluminosilicate fluoronated it while the silicon dioxide (Yes, Virginia, there is a silicate mineral called quartz). The variety of quartz is due to dirt and I think the variety of topaz smoke is due to the same thing. The best way to distinguish is a hardness test: Topaze (Mohs hardness of 8) to remove the quartz (Mohs hardness 7), although the amount of force required may exceed what some people can exercise . Topaz crystallizes in the orthorhombic system (where each angle is ninety degrees) and quartz crystallizes in hexagonal crystals.