“Minerals that do things…”
Hands-on demonstrations of mineral properties
Provided for the Mineral Information Institute by Andrew A. Sicree, Ph.D.
Can you fi nd the real diamond?
Object: If you purchase diamond jewelry, how do
you know you’re buying a real diamond?
Students will learn how diffi cult it is to
pick out a real diamond from among
fakes. If diamond simulants are hard to
distinguish from real diamonds, should
you spend lots of money on real gems?
Procedure description: Use a diamond tester. Test
a number of likely-looking specimens.
First, the student looks at the specimens,
then guesses which ones are diamonds,
and then uses the diamond tester to test
each specimen. Students will fi nd that
many of the diamond fakes and simulants
are hard to detect.
Specimens to test: (all should be roughly the
same size) Faceted stones: inexpensive
diamond(s), small (0.1-0.2 carat are
fi ne) – can sometimes be obtained from
old inexpensive jewelry; moissonite;
quartz; rhinestone(s); cubic zirconia;
clear aluminum oxide, or other clear or light-yellowish gemstones. Rough, uncut materials:
diamond crystal(s); diamond(s) as chips or grit (may be obtained from old diamond drill
bits); bort; carborundum; moissonite; quartz; Herkimer diamond; glass; cubic zirconia;
other clear synthetic rough. Ideally all of the specimens would be small and roughly the
same size as your true diamond(s).
Equipment Needed: One electronic diamond tester. One of the old-style thermal conductivity
probes is best – ask a jeweler to loan/give/sell his old one – many jewelers had to buy new testers
because the older probes could not separate moissonite from diamond. Specimens should be
adhered to a wooden board. A dark stained hardwood is best. Faceted specimens may be glued
to the board – fi rst make a dimple in the wood with a large nail or the tip of a pointed chisel, then
glue faceted specimens in place with epoxy glue. Rough material should also be attached to the
Ideally, you will hav