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Gemstones

Articles from GEMSTONES - SYNTHETIC (54 Articles)











Image from L to R: Raw synthetic moissanite material before being grown. Source: Alibaba | Cut and set moissanite Source: Diamond Boutique
Image from L to R: Raw synthetic moissanite material before being grown. Source: Alibaba | Cut and set moissanite Source: Diamond Boutique

Synthetic Moissanite

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.

Pronounced moy-san-ite, from the name of French chemist Henri Moissan, it is often marketed as affordable diamond alternative.

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.

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: SiC2

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. 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.











ABOUT THE AUTHOR
Susan Hartwig

Susan Hartwig FGAA came late to the world of gemmology after a long career in corporate training and project management. She combines her love for writing with a passion for gems and jewellery. Susan writes regularly for her gemmology blog ellysiagems.com. For more information on gemmology courses and gemstones, visit: gem.org.au

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Wednesday, 03 June, 2020 01:57am
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