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GEMSTONES

Magnificent cornflower Vietnamese over 10 carats in size. This type of colour is considered to be the most expensive. ©Yavorskyy, Bangkok

Spinel’salluring features By Dr. A. Peretti pinel, an ancient , has experienced an enormous shift in popularity over the last decade. For centuries, the transparent stone Swas coveted by royalty, especially when found in large sizes like the famous Samarian Spinel from the Iranian Jewels, considered to be the largest of its kind at 500 carats. Several British include vivid spinel, like the famous Prince’s , erroneously named because at the time of its discovery there were no scientific methods for separating similarly coloured . Spinel may have also occurred in deposits where ruby was found, further complicating its identification in earlier times.

Attributes of its value Like any precious stone, there are traits it needs to sustain its appeal. Beauty, rarity and durability of the stone are key factors, but colour is also critical for its wide acceptance. Fortunately, spinel occurs in a variety of colours besides the red favoured by royalty. Spinel is one of very few gemstones that occurs in a vast array of colours, including blue, ranging from greyish-blue to . It is also found in a wide range of from vibrant pinkish-red to vivid red, plus oranges and all kinds of fancy colours. Besides its rainbow of colours, another winning feature of spinel is that it occurs in large sizes, often combined with good clarity. With a hardness rating of 8 on the Mohs scale, spinel is a very durable material. Gem-quality spinel, often found in the same deposits alongside ruby or , is a very rare occurrence today.

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(Top) A set of three faceted Sri Lankan ranging from 12 to 16 carats in size. A typical colour variety of this origin is the pastel purple to ‘lavender’ colours. © Yavorskyy, Bangkok

(Left) A tray of faceted Burmese spinel at the gem market in . (Right) Vietnamese spinel with star effect formed by inclusions of silk arranged in three different directions. © GRS Gemresearch Swisslab

Regions determine colour have also surfaced in the Mansin Undisclosed enhancements plays an important mines located in the Mogok (ruby and sapphire) role in where certain colours of Valley. Beside the vivid red spinel has been dealt a shattering blow spinel are found. The most sought- varieties, the attractive pinkish- in recent years upon revelations after colours in spinel are vivid reds garner the highest prices for of non-disclosed product red and cornflower blue. The vivid spinel around the world. Alongside enhancements such as - red varieties are found principally the more recently discovered treatment, lead-glass treatment, in the Mogok Valley in Burma or deposits, the classical and high-temperature treatment with . On the other hand, the historically known spinel fissure healing and the resurgence cornflower blue material is derived sites in the Pamir Mountains of conventional diffusion-treatments. mainly from , but it can of have resumed This has resulted in a loss of also be found in and production, unearthing important consumer confidence that has yet . This blue variety has large stones over 40 carats in to be fully recovered. Spinel, by become known in the trade as size. Not all spinel is recovered contrast has remained free of such Spinel. from mountainous mining sites, disgrace since it has not been In the last decade, the however. Ancient river sites, known subjected to similar covert and discovery of spinel deposits in as alluvial deposits turn up spinel widespread treatment. Recently, Vietnam, Tanzania and Northern in Tanzania, Vietnam, , co-diffusion and heat-treatment has Myanmar’s (Burma) Namya region Sri Lanka and Myanmar (Burma). appeared in spinel but fortunately it took the gem world by surprise Primary marble deposits in can be easily detected. with the production of incredibly Myanmar (Burma), Vietnam and beautiful colours, such as the Tanzania, and veins within Impact of Act vibrant pinkish-red spinel from marble deposits of Tajikistan are Before the new generation of Namya. Similarly striking colours also a source of spinel. African ruby was discovered in

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Left: Men at work at an alluvial spinel and sapphire mine in Ilakaka, Madagascar. The mine is called ‘The Swiss Bank’ mine due to the large number of valuable gems found there. © GRS Gemresearch Swisslab. Right: A 108- rough red spinel (right) from Tajikistan cut into a 33-carat magnificent masterpiece (left). The mine in the Pamir Mountains has been active for hundreds of years and has produced many crown jewels and some of the largest spinels ever unearthed. © Yavorskyy, Bangkok

Tanzania (Winza) and , of human rights violations occurring the auction houses to pay serious spinel was considered a highly in that country. With that embargo attention to the importance of spinel. desired alternative to the ever in place, the international gem increasingly rare ruby emerging from trade scrambled to fill the demand Price hike the classical Myanmar (Burmese) for top-quality ruby by looking for The rise in popularity of spinel is origins. Then in 2008, the ban close alternatives like fine spinel. of course reflected in its price surge on Burmese ruby, called the Tom This refocus actually provided a as shown in the chart above. In the Lantos Block Burmese JADE big pay-off in bringing interesting last five to 10 years, spinel prices (Junta’s Anti-Democratic Efforts) Act, new colours to the fore especially have increased more than 10-fold quashed all importation of Burmese where couture high- was depending on its colour and origin. ruby and jade into the US in protest concerned. This in turn caused Today, spinel prices are comparable to those of unheated sapphire; this Price increase between 2002 and 2012 for selected is particularly true with cornflower blue spinel from Vietnam or vivid “Top-Quality”Price increase between 2002 Burmese and 2012 for “Top Ruby,Quality” of selectedSapphire Burmese Ruby, and Sapphire Spinel and Spinel red spinel from Myanmar-Mogok 120,000 (Burma) and vibrant red spinel from Mahenge, Tanzania. 100,000 Pigeon's Blood Ruby - (5ct) The principal attribute of spinel’s surprising discovery to the 80,000 2008 Sapphire - (20ct) Global Financial Crisis gemmological world is its immense & Tom Lantos JADE Act 60,000 Vivid Red variability by colour and geographic Spinel - (5ct) traits particular to specific regions. Price per carat in USD Price per carat in USD 40,000 This is an enormous help to researchers in separating spinel 20,000 by origin and identifying treatments in the microscope (see book, 0 2002 2006 2007 2008 2009 2010 2011 2012 The World of Magnificent Spinels 4 years Year - Provenance and Identification - In the years between 2002 and 2006, the prices for the above selected Burmese gemstones approximately doubled. After the Burma ban in 2008 (Tom Lantos Block Burmese JADE Act), the prices for top-quality“Pigeon’s Blood” Contributions to , No. escalated most dramatically along with the other gems shown above. escalated most dramatically along with the other gems shown above. 11, 2011, reprinted The prices for vivid red spinels have risen more than 10-fold since 2002. A 5-carat vivid red spinel’s price in 2013 is at the same level as a 5-carat “Pigeon’s Blood” ruby’s was back in 2008. February 2014, available in February 2014 from GRS Lab HK Ltd). The prices for continuously increased and the gap between sapphire and spinel prices became smaller. A further price increase of around 50% is estimated in 2013 in comparison with the year 2012. A 1-carat “Pigeon’s Blood” ruby is currently worth around $7,000, roughly 10 times more than in 2008. The author is the founder of All example Burmese gemstones. Source: Contributions to Gemology No. 14, 2013 - available from GRS Lab (HK) Limited GRS Gemresearch Swisslab. JNA

64 ︱January 2014