Jewellers' Network

Category: Gemstones

Synthetic Moissanite vs Diamond

The Devil is in the Detail
We’ve spent a lot of time this month talking about the differences between synthetic and natural gemstones, as well as the benefits of including synthetics in your range of jewellery. After all, if a customer can’t afford a diamond, then doesn’t it make sense to be able to offer the next best thing? Before we do, however, I feel that we need to clarify a few facts, notably with regard to diamonds and what is considered their imitation counterpart – that being synthetic moissanite.

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AG&J Responds To GIA Decision To Grade LGD With Same Terminology As Natural Diamonds

New York, October 20, 2020
AG&J -Analytical Gemology and Jewelry head Dusan Simichas launched a response to the decision of the GIA to grade laboratory-grown diamonds in what he calls a standardized fashion.

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Synthetic Moissanite vs Synthetic Diamond

There seems to be a lot of demand for an alternative to “earth mined” diamond these days. Some are doing it for ethical reasons, some for nature conservational reasons and for others it is purely economical.

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Federation of Southern African Gem and Mineralogical Societies

Federasie van Suider – Afrikaanse Siersteen – en Mineralogiese Verenigings

Read our second newsletter of 2020


Ancient Egyptians mined them in Egypt and as their national gemstone it was known as the ‘Gem of the Sun’.

A symbol of strength bringing happiness, good cheer, attracting love, improving eyesight and freeing the mind of envious thought are just some of the mystical wonders of this gem. Continue reading…

The Pegmatite Mines of Mozambique

Co-authored by Arthur Thomas FGA(GB), GG(USA), CE(RSA) and Craig Thomas FGA(GB), GG(USA), B.Comm(RSA).

The three major, extensively-worked, mineral rich pegmatites in Mozambique run from the Muiâne mine of Alto Ligonha province in the north, by way of the central Morrua Mine to the Marropino Mine of Zambeze province in the South.

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How Are We Going To Protect Our Industry?

There’s no denying the value of associations which exercise a level of authority within an industry. In fact, if it weren’t for these, there would be far more cowboys in the building trade and a free-for-all in the financial sector for starters. Continue reading…


The word Emerald is derived from the Greek word “Smaragdos” which means “green stone”. The Emerald is a member of the Beryl (beryllium aluminium silicate) family. Elements of chromium in the crystal produce the colour, while inclusions in the stone create what is called the jardin, or garden, of the emerald. Continue reading…

Got a pocket full of Sunstone?

Maybe think twice

BY Kaylan Khourie, FGA

Sunstone falls part of the Feldspar mineral group. It is known for exhibiting what is called “Aventurescence. Aventurescence is a type of iridescence (a play-of-colour) that is caused by the reflection of small, thin and platy inclusions – copper, goethite and/or hematite in the case of Sunstone – that are spread in a parallel orientation through the gem. Continue reading…

March Birthstone: Aquamarine


Aquamarine, birthstone of March, is from the family of beryl which is a harder gemstone and makes it suitable for everyday wear.

The name aquamarine was given because of its beautiful pastel blue and hints of green and is reminiscent of the seawater.

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Coloured Stone Grading

Welcome to part 3, 4 and 5 of our mini-course on coloured stone grading. Last month we looked at the key role colour plays in assigning a grade value to a gemstone. This month, we’re diving into clarity, Brilliancy and Final Adjustments


What do we mean when we talk about gemstone clarity?

Clarity refers to the degree to which a gem is internally included and/or flawed. It is interesting to note that these flaws don’t just affect the appearance of the stone: they can have an impact on its durability, as well. The grade is assigned based on just how visible those inclusions are. It is also affected by whether or not they can be seen with the naked eye, or if magnification (for instance, using a jeweller’s loupe) is needed to spot them. 

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Meteorite is defined as a piece of debris from a comet, asteroid or meteoroid that survives its passage from outer space to impact the surface of a planet.

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Natural and Artificial Glass

In his daily routine the average jeweller is sure to encounter glass in many forms. These range from the cheap moulded pastes that are mounted in costume jewellery or massed produced 9ct settings to the rare natural Moldavites that may be encountered set in fine antique pieces.

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Coloured Stone Grading

ICSL (Independent Coloured Stone Laboratory) grading system.

Like many leading gem laboratories around the world, at The Gem Lab we grade all coloured stones according to the ICSL grading system. This internationally recognised industry benchmark grading system applies to all gemstones.

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Don’t Believe Everything You Hear

The value of gemstones lies in their beauty – and how long it lasts.

These attractive stones never lose their magic, and this quality gives them worth for centuries. Jewellery is a rare kind of investment: it grows both more beautiful and more valuable with age.

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The Garnet Family (Part II)

Andradite garnet (Ca3Fe2Si3O12)

This calcium iron garnet occurs in metamorphic environments frequently as the result of alteration in bodies of impure limestone. It is generally associated with chlorite, diopside, mica and serpentine. Andradite varieties include demantoid, melanite and topazolite. Demantoid, the most sought after variety, was named for its diamond like lustre and brilliance. Continue reading…

Gemlab – Old Gemstone Enhancement Beliefs

Extract from ‘Gemstone Enhancement’ by Kurt Nassau

One of the important tasks of the gemmologist is to identify treatments which may have been used to modify the colour or appearance of the gemstones being examined. Today we are faced with sophisticated methods of gemstone enhancement such as beryllium diffusion treatment, irradiation, coating etc. One needs to be aware of the treatment used for each species of gemstone and test them accordingly. Continue reading…

Synthetic or simulant


The term “synthetic” has been very controversial lately so let us explore the definition so that we may better understand the meaning behind this word.

Firstly let’s define the word artificial. Artificial means made or produced by human beings rather than occurring naturally. Artificial is a broad term used to describe both synthetic and manmade imitation gems. Continue reading…

The Garnet Family (Part I)


The garnets form a complex family of silicates. All its members consist of a combination of divalent and trivalent metallic elements with a typical silicate base.

The ruby red Bohemian pyrope so frequently encountered in Victorian jewellery is a magnesium aluminium silicate with a hue that is enriched by a generous trace of chromium. Continue reading…

What About the Other Synthetics?

When we speak about synthetic gemstones you may immediately think of synthetic sapphires, rubies, emeralds, and diamonds, and you wouldn’t be wrong.

As I have mentioned in one of our previous emails, most of the synthetic gemstones that are tested by our lab have been produced by the Verneuil process, which has been around since the late 19th century. However, the more sophisticated synthetics like Russian emeralds require a lot more knowledge and experience to identify and at times the use of very expensive equipment.Did you know that in our lab we also see synthetic coral, turquoise, star rubies, lapis lazuli and opals to mention just a few? All of these synthetics have the same chemical composition, optical and chemical properties as the natural stones, but these very seldom get a mention in trade discussion. Continue reading…