Jeweller - April 2020

LEARN ABOUT
Gems
Synthetic Moissanite
L to R: Raw synthetic moissanite material before being grown. Source: Alibaba | Cut and set moissanite Source: Diamond Boutique
Synthetic moissanite is marketed by
the jewellery industry as an affordable
diamond alternative. Named after Nobel
Prize winner and French chemist Henri
Moissan, moissanite in its natural form
is a rare mineral, silicon carbide.
In 1893, while inspecting minerals from an
Arizona meteor crash site, Moissan initially
thought he was looking at fragments of
diamonds. It wasn’t until 1904 that he
correctly identified the samples as being
silicon carbide.
It was an understandable mistake, given
the testing instruments of the time.
Too rare in nature to meet the demand
from various industries, moissanite was
synthesised in the early 20th Century for
applications similar to those of diamond: as
an industrial abrasive and cutting material.
With hardness of 9.25 on Mohs’ scale
and the capacity to withstand extreme
pressure – both essential properties for
use in industry – synthetic moissanite was
a cheaper resource than diamond and one
that could be readily created in quantity.
The properties that made moissanite
of value in electronic circuitry and highpressure
testing, eventually captured
the interest of the jewellery industry.
Hardness and durability, plus moissanite’s
high dispersion – 0.104 compared to
diamond’s 0.044 – when faceted, made the
synthetic material an ideal alternative
to natural diamond.
Synthetic (laboratory-grown) moissanite
was introduced to the jewellery world by
American firm Charles & Colvard in 1998
under several brands, namely Forever
One, Forever Brilliant and Forever Classic.
There are now other manufacturers and
a range of trademarked names.
Without access to specialised gemmological
instruments, distinguishing synthetic
moissanite from diamond requires a
trained eye.
Colourless laboratory-grown moissanite
ranges from D to K on the GIA Diamond
Colour Scale.
Gems within I to J and below on the colour
scale, although still technically ‘colourless’,
may display a faint yellow, grey or greenish
tinge.
Laboratory-grown moissanite can display
a rainbow-like ‘flash’ in natural light due
to its high dispersion.
Some laboratory-grown moissanite will
have a whitish appearance compared
with a diamond.
With bright vitreous lustre and an eyeclean
appearance, the task of separating
laboratory-grown moissanite from
diamond might be considered difficult.
Moissanite
Pronounced moy-sanite,
from the name
of French chemist
Henri Moissan.
Often marketed as
affordable diamond
alternative.
Colour: Colourless
but usually tinged
with a greenish hue
compared to diamonds
Found in: US, Turkey,
Russia – though
usually synthesised
Mohs Hardness: 9.25
Class: Silicon carbide
Lustre: Adamantine
to metallic
Formula: SiC 2
However, with the aid of a 10X loupe,
this is a relatively easy task.
Laboratory-grown moissanite often shows
fine whiteish needle–like inclusions. Look
for these through the table. Laboratory
grown moissanite will also show double
refraction; this feature is an obvious
indication you are not looking at a diamond,
which is a singly refractive gem.
To observe double refraction, using the
loupe, look through the table towards the
culet and you will see doubling of the facet
junctions. Still looking through the table,
focus on the girdle; doubling will be obvious.
Unlike a diamond’s sharp facet edges,
those of laboratory grown moissanite
will be rounded and less sharp.
For customers seeking an affordable
diamond alternative, laboratory-grown
moissanite is a good choice.
It has more fire, is harder and is more
durable than other alternatives, such
as cubic zirconia and natural gems like
colourless zircon or sapphire.
Susan Hartwig FGAA combines her love
for writing with a passion for gems and
jewellery through her gemmology blog,
ellysiagems.com. For more information
on gemmology courses and gemstones,
visit gem.org.au
April 2020 | 17