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Jewelry, Gems, & Minerals/identify rough uncut gems



possible sapphire
possible sapphire  
Do these look of any interest to you?  Tell me how I can help you identify these stones with any furthur images, please.  The blue star sapphire looking one is approximately 1 in. base by 3/4 ht. It is 7 sided with base.   The other image (scepter) 1 1/4 in. in length by 1/2 width. It is dark purple. green, and a clear eye.  Thank you so much for your time and expertise...

There are several ways of determining the identity of your gem mineral. Most of them will need specialized equipment which can be costly. There are, however, some easy, DIY tests you can do that would point you at least in the right direction.
You might test your specimens for hardness. Get some cheap quartz crystal (rock crystal) from a rock shop. The quartz should have flat crystal faces. Try to scratch one of the crystal faces on the quartz with your specimen. (Push hard and don't be too timid, but not so hard as to break your sample). Sapphire is a type of corundum which is extremely hard (MOHS hardness of 9) and should leave a visible scratch on the quartz crystal face. But some other blue gems might scratch quartz as well, such as topaz.
The second test is for Specific Gravity or Density. You can build your own very accurate specific gravity / density system using one of the papers I wrote as a reference: Kackstaetter, U.R., 2014, A Rapid, Inexpensive and Portable Field and Laboratory Method to Accurately Determine the Specific Gravity of Rocks and Minerals: The Professional Geologist  Vol. 51:2, p.56 - 60. The publication is available at: (Just go to p. 56 after download)
Sapphires are fairly dense and should measure around 3.98 g/cm^3 (give or take). Numbers significantly less than that and you do not have a sapphire. Measurements around 2.7 g/cm^3 may indicate an iolite (the blue variety of the mineral cordierite).
I hope this helps and is not too technical.  

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Uwe Richard Kackstaetter, Ph.D. (Dr.K)


I can answer questions concerning minerals, mineralogy, gems, metals, and anything that has to do with geology. However, I am NOT a jeweler. Questions about values, settings, gem stone cuts and appraisals are best directed to other experts on this site. I can however aide in the identification of unknown mineral materials. As a public service and part as training for new geoscientists, our university department provides FREE mineral identification for individuals. Please contact me for details or go to for details..


I am a professor of applied geology and mineralogy with many hours of field experience. Furthermore, I enjoy recreational gold prospecting and mineral collecting. As a professor I am engaged in research concerning minerals and their occurrence.

Member of the GPAA (Gold Prospectors Association of America) as well as the Association of Environmental Geochemists. Member of the GSA (Geologic Society of America) Member of the AIPG (American Institute of Professional Geologists)

Here is a small sampling: Mineral-rock handbook: Rapid-easy mineral-rock determination : written for anyone interested in minerals and rocks - Proctor, Peterson, and Kackstaetter;Macmillan Pub. Co. (New York and Toronto and New York) Physical Geology Laboratory e-Manual [CD-ROM], Kackstaetter, Earth Science Education LLC Colorado Front Range Self-guided Geology Field Trips, Kackstaetter,

Ph.D. in Applied Geology and Mineralogy. I am actively teaching courses in mineralogy and a variety of field courses with mineral collecting opportunities. Background in precious metal exploration.

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