Jeweller - May 2021

REVIEW
Gems
Behind every gemstone,
there is a fascinating story
waiting to delight clients
around the world. Studying
with GAA brings the
expertise, networking and
confidence to build a solid
career in a multimilliondollar
industry. Joining
one of the most supportive
and passionate professional
communities of gemmologists
in Australia was one of the
best decision I ever made.
Gina Barreto FGAA DipDT
Gemmologist and Diamond Technologist
Be
Diamond
Courses
Confident
Passionately educating the industry, gem enthusiasts
and consumers about gemstones
Practical Diamond Grading
Advanced Practical Diamond Grading
Diploma in Diamond Technology
Enrolments now open
For more information
1300 436 338
learn@gem.org.au
www.gem.org.au
Gem-Ed Australia
ADELAIDE BRISBANE HOBART MELBOURNE PERTH SYDNEY
The magic of moonstone
The aptly named moonstone has been
associated with the moon across various
cultures throughout history. In Hindu
mythology, moonstone is believed to be made
of solidified moonbeams.
This gemstone has the ability to interact
with light in such a way that it resembles
moonlight shining across the ocean or
through a veil of clouds. Historically,
legends tell of moonstone bringing its
wearer good luck.
The captivating gem is generally semitransparent
to translucent, displaying a
milky, silvery white sheen through to the
more desirable blue sheen.
This blue, in a more transparent stone, is
the most valuable, sought-after, and difficult
to source form of moonstone. Other colours
include beige, brown, yellow, reddishbrown,
greenish, orange, and grey.
Moonstone is generally readily available,
including the cat’s eye (chatoyant) variety,
but is scarcer in higher quality material and
larger sizes.
An interesting and characteristic feature
that may be found in these specimens is an
inclusion called centipedes – long, minute
tension cracks with shorter perpendicular
cracks overlapping.
Moonstone is a member of the feldspar
mineral group, specifically being composed
of two feldspars – orthoclase and albite.
These two varieties grow parallel to each
other within the stone, causing light to
scatter and reflect off the multiple layers
producing the silvery white phenomenon
known as ‘adularescence’ or ‘schiller’.
When these layers of orthoclase and albite
are thinner and consistently spaced, the
adularescence effect is progressively bluer.
This adularescence gives moonstone its
prized ‘glowing’ appearance, which rolls
over the stone as you move it and change
the angle of view. This makes it ideal for a
cabochon cut – particularly with dimensions
uniform and not too flat – as this enhances
and highlights this sheen.
The word adularescence comes from the
gemstone’s original name, ‘adularia’, after
Mount Adular in Switzerland where the first
high-quality material was found.
Today, gem-quality moonstone is found
in locations including Madagascar and
Tanzania, with the finest in Sri Lanka,
southern India, and Myanmar (Burma) in
limited supply.
When cut correctly en cabochon, this multitalented
stone may also exhibit chatoyancy,
including asterism, with a four-rayed
star caused by the same layered feldspar
structure that causes the adularescence.
Other cutting techniques include faceting,
which offers increased brilliance, and
carving, such as a face representing the
‘man-in-the-moon’.
With a hardness of 6–6.5 on Mohs’ scale,
and cleavage – a plane of weakness – in
two directions, this gem is better suited to
L to R: Anna Hu brooch; Fred Leighton necklace; Neha Dani bracelet
Below: Mvee ring; Nicole Mera ring
Moonstone
Named for its
moonlight-esque
sheen; originally named
adularia for Mount
Adular in Switzerland
Colour: Blue, green,
white, yellow, pink,
purple, orange, grey,
and brown
Found in: Sri Lanka,
India, Madagascar,
Tanzania, Myanmar
Mohs Hardness: 6–6.5
Class: Feldspar
Lustre: Vitreous
pendants, earrings, and brooches rather
than rings.
To care for moonstone, it’s best to steer
clear of ultrasonics and steam cleaners
and opt for warm soapy water instead. It is
susceptible to damage when exposed to a
sudden shift in temperature, high heat, or
hydrofluoric acid.
This gemstone was a popular choice among
jewellery artisans of the Art Nouveau era,
including Louis Comfort Tiffany and René
Lalique. The stone can be found featured
in notable works such as special, singular
commission carvings by Fabergé and
oriental-inspired Art Deco clocks by Cartier.
Like many gemstones, imitants are available
on the market, either intentionally designed
to fool or coincidentally resembling
moonstone. Some of these include synthetic
white spinel heat-treated to give the
adularescence effect, opalescent glass,
chalcedony with a milky consistency, and
even heat-treated amethyst.
To this day, this beautiful gemstone
offers jewellery design with the same
romanticism and mysticism we associate
with moonlight.
Mikaelah Egan FGAA Dip DT
began her career in 2015 with an
independent manufacturing jeweller.
She now balances her role as a
gemmologist and design consultant
at Vault Valuations in Brisbane with
pursuing studies in geology. Visit
instagram.com/mikaelah.egan
May 2021 | 30