About
The content on this site is edited, written, or maintained by a certified crystal identifier.
Gemmological Institute, China University of Geosciences — April 2026
Subject matter
Quartz and quartz-family minerals: how a specimen is identified, where the material comes from, how it may have been treated, and what those treatments look like under examination.
Instruments
Every check described on this site can be performed with four things: the unaided eye, a 10x loupe, a directed light source, and a polariscope. Where a check needs one of them, the article says which.
What these checks cannot do
Examination by eye and loupe does not produce a laboratory certificate and does not replace one. Where a specimen is worth more than roughly US$300, the correct step is a report from a testing laboratory. Each article also states the conditions under which the method in it stops working.
Dates
Every article carries the date it was published and the date it was last revised. Where a revision changes a conclusion, the change is stated in the article rather than made silently.
Contact
Corrections to anything published here, questions about a method described in an article, and press or permission requests all go through the same form as submissions.