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QUARTZ : I would suggest becoming familiar with the refractiveindex of quartz unless you prefer to do the acid test.With a loupe, a light source and a few seconds youshould be able to positively differentiate glass fromquartz. You might benefit from reading Hodgkinson andHanneman (J. of Gemology, Jan. 1979) under the term"Visual Optics" (acomplete bibliography can be found at the end of thearticle)I understand the difficulty with purchasing online, canyou not insist on CC payment to provide some recourse.JeremyIf you can locate a Polariscope the Quartz should "blink" when rotated andthe glass will not.If you know a gemologist in your area or a faceter theyshould have one. I am in N.C. if that helps.If you have a short-wave black light, or know someone that has one, you cantell by comparison. Clear quartz (with no impurities) won't flouresce, whilemost glass does flouresce slightly. If you compare a known glass bead withyour clear quartz specimen, you should be able to tell when viewed undershort wave black light in a dark room.
QUARTZ : Howdy Sphuratta, You should try to familiarize yourself with the way quartz and glassfeel against your cheek or lip. If 2 items are sitting on a table atroom temperature and one is common glass (perhaps not pyrex) and one isquartz the quartz item will feel cooler. Of course if you hold or handlesmall items for long they begin to warm to skin temp. and thedistinction may be lost. Experiment. Other than the above you would need some equipment to measure RI,specific gravity and look for tell-tale inclusions (most glass will have'flow-lines' and perhaps bubbles). Or, only purchase with return guarantee and locate a gemmologist nearyou to perform the test.Carl1 Lucky TexanSphuratta, The methods suggested by others in this group to differentiateglass from quartz are all very good, especially if two or more tests areused. To recap and add to what has already been said:Quartz is a crystalline substance and glass is a super-cooled liquid.Because of this, they have different physical and optical properties. Quartzis harder than glass and can scratch it. Glass will not scratch quartz.Quartz is anisotropic and glass is isotropic. A simple test to demonstratethis is to make a polariscope ( remove the lenses from a pair of Polaroidsun glasses, put one on top of the other and rotate the top lens until allthe light is blocked. You now have "crossed" Polaroids. Keep the lenses inthis orientation, this is a polariscope.) Now place the gem, beads, orsample between the crossed lenses. Rotate the object while keeping thePolaroids steady, Quartz will blink, light and dark allowing light to passthrough the Polaroid sandwich in various orientations.Glass will remain dark(note, some glass is strained and show some light areas under thepolariscope).
QUARTZ : Most glass will fluoresce under short wave ultra-violet light and mostquartz will not .If you have a large enough bead or sphere, you can see double refraction byplacing the object on news print and rotating the piece. In certainorientations the letters of the print will appear doubled. Glass won't dothis. Often you can see this doubling effect on inclusions such as bubblesin quartz. You may need a hand lens to see this.There are other tests, but they remind me of the testing methods for diamondused by the 49' ers during the California gold rush. "Just put the stone onan anvil and hit it with a hammer, if it shatters, then it is not diamond"Hope this helps, Will EstavilloI think lots of diamonds must have gotten broken into a million pieces!
QUARTZ : I heard that a quite large RED diamond was either destroyed (or perhapsre-cut and resold) by this 'test'. I think I heard that many of thepieces of the stones that 'failed' the test were re-cut too. Perhaps oneof the first diamond scams.Carl1 Lucky TexanI thank you all for your very helpful suggestions. You have given me muchfood for thought!However, being a neophyte to gemmology, I soon realized (!) that there wasno way I could successfuly implement some of your suggested techniques forauthenticating quartz to arrive at my own conclusive verdict. For example, Icould not tell whether my quartz rosary was "fluoresce"ing or not. This termis new to me. And also, even if it did really "blink" back at me, I couldnot recognize it. ??? (If you asked me, to my inexpert eyes, my rosarywinked at me more than it blinked. ;-)
QUARTZ : Can anyone please explain or give a definition of high quartz/beta quartzand what exactly happens when you heat quartz above 573 C.? Another question: will it remain in this form, or change as it cools? Any answers, locations for info. would make me :). thanks.Beta quartz exists only briefly after its crystallization as phenocrystsin siliceous volcanic lava and yields its identity to the stable alphaform before the lava cools. Only the stuby bipyramidal habit and intensefracturing remain to tell of the existence of beta quartz. Although allquartz found in nature is alpha quartz, crystals of high temperature betaquartz form in some lavas and tuffs, but invert to the alpha structure asthe lava cools below 573 C.A definition may be "beta quartz is the polymorph of quartz that is stablefrom 573 to 870 C, and that has a lower refractive index and birefringencethan those of alpha quartz. It occurs as phenocrysts in quartzporophyries, graphic granite, and granite pegmatites."
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