Jeweller - February 2019

GEMS
COLOUR INVESTIGATION: BERYL (PART 2)
burn off the salmon colours to allow
for more ‘in vogue’ pink tones. Like
aquamarine, the crystals can be quite large,
free of inclusions and pale, so larger faceted
gems are fashioned to give the depth of
colour preferred.
Morganite is dichroic, showing two distinct
colours, a pale pink and a darker bluish pink,
when viewed in different directions. It must
be cut very carefully to obtain the best colour.
Morganite can resemble pink topaz, pale pink
spinel and pale pink sapphire.
The colour of heliodor beryl varies from pale
lemon to rich gold. Its name comes from
the Greek meaning for Sun (helios) and gift
(doron). It is an inexpensive beryl that can be
mistaken for citrine, but it is not frequently
used in jewellery due to higher popularity in
other beryl gemstones.
In our previous issue KATHRYN WYATT
introduced the beryl gemstone family
and paid attention to its most famous
member: the emerald. Here, she
examines other varieties, including
the aquamarine, morganite, heliodor
and goshenite.
Beryl is a beryllium-aluminium silicate, with
its non-gem material mined for its beryllium
content. It’s a very light metal with a high
melting point and elasticity, which is used
in industry alloyed with other metals. Pure
beryl is colourless, but most gem quality
material is transparent and coloured by a
variety of trace element impurities creating a
range of lovely hues.
an emerald cut, so green beryl needs to
be cut as deep stones to show depth of
colour. Luckily, unlike emeralds, green beryl
and other paler colours can come in large
crystals with few inclusions.
The colour of aquamarine beryl (named
from the Latin aqua marina, meaning
sea water) is greenish-blue to blue-green
(dichroic or showing 2 colours), caused by
impurities of iron oxide. Most aquamarines
are heat treated to remove green tinges
because blue hues are considered more
fashionable. It can be confused with blue
topaz. Aquamarine is usually cited as the
birthstone for March. It makes wonderful
cocktail rings due to the large cuts!
PINK BERYL
IS KNOWN AS
MORGANITE,
NAMED AFTER
THE AMERICAN
FINANCIER AND
GEM COLLECTOR
J. P. MORGAN
The colourless goshenite is probably the least
known beryl. It was named after Goshen,
a place in Massachusetts where it was first
discovered. It makes for a lovely stone when
cut, and it has been used to imitate more
precious gemstones such as diamond.
Beryl is found mainly in pegmatites (notable
exceptions are emeralds in mica schist in the
Ural Mountains and limestones in Columbia)
and in a variety of localities around the
world. All beryls have a hardness of around
7.5 on Moh’s scale, sufficiently hard for
everyday wear. They all tend to brittleness, so
must be cut very carefully, both to minimise
the chance of accidental fracturing and to
obtain the best depth of colour. Beryl are all
dichroic and are often heat treated to make
the colour purer. The brilliance and colours
of well-cut beryl make it one of the most
versatile gem families. i
Part 1 analysed the emerald, the popular
beryl gemstone that radiates a verdant
green colour, however, there are also paler
green tones, which are simply named green
beryl. Beryl’s brilliance is best shown with
Pink beryl is known as morganite, named
after the American financier and gem
collector J. P. Morgan. Its colours include
pink, rose, peach and salmon, which are due
to traces of manganese. It is often heated to
KATHRYN WYATT is a qualified gemmologist,
diamond technologist, registered jewellery valuer,
educator and member of the Gemmological
Association of Australia. For information on
gemstones, visit: gem.org.au
February 2019 Jeweller 33