Spotlight on the gem world: Padparadsha sapphire.Padparadsha is the name given to this gorgeous deli

Spotlight on the gem world: Padparadsha sapphire.Padparadsha is the name given to this gorgeous delicately blended rosy-peach colour in sapphire, and good quality stones are very rare. The name originates in Sri Lanka (Ceylon) where these stones traditionally came from. It supposedly reflects a specific colour of lotus, though the origins of the term are lost in the mists of history. Most lotus flowers now found in the subcontinent are pink, without the orange colour component. This colour is also found in Vietnam, Tanzania and Madagascar though true purists only accept Ceylon stones as the real McCoy.There is alot of discussion in gemmological circles about how to define the colour- the only consensus, so far, is that both pink and orange have to be present, roughly equally, and the tone cannot be too dark. Colour is separated into three components: Hue (red, blue), tone (light or dark) and saturation (how much colour is present- for example pink is a low saturation red). Brown colour modifiers should be absent, and the colours should be evenly blended within the stone rather than patchy.Pink and yellow/orange sapphire have to be combined in the same stone, and unlike other colours, low saturation to medium stones display more delicate and subtle shades. Pink sapphires are coloured by chromium (see our past posts on chromium in gems at http://tinyurl.com/c8uhnc9 and http://tinyurl.com/dxwv9zo), yellow sapphire by iron, and the spectrum of both should be visible in the hand spectroscope.Most commercial sapphires on the market have been heat treated in an oven, in either a reducing or oxidising atmosphere, depending on the type of starting rough and the desired result. This process enhances both colour (by removing a brown component for example) and clarity (by dissolving cloudy inclusions of rutile within the stone). This treatment is stable and fully acceptable in the gem market, as long as its presence is disclosed to the buyer. No-one but the very rich would be able to afford ruby or sapphire otherwise. Other treatments are not so welcome.Stones are often roasted in a flux, usually a lead glass of varying composition. This melts and can fill cracks in the stone, adding non gem material to its weight. Some stones are riddled with such glass filled cavities, which are identified in two ways: The glass usually has a different refractive index than the gem, and the different lustre of the reflected light off the two materials should be obvious. The second is to look for a blue or pink flash in the handlens as the stone it tilted back and forth in a strong light. Murkier practises include adding artificial yellow-orange colour by beryllium diffusion treatment, which is hard to detect. This is why it is useful to have a certificate from a gem laboratory for expensive stones: all treatments should be revealed under professional examination.Natural untreated padparadsha is very rare and expensive, rivalling fine rubies or emeralds, and trade at a high premium compared to roasted rocks. Superior quality gems trade for as much as $30000 a carat, though like with all gems, low quality shlep is available at a few dollars a carat. Since they are so rare, most such sapphires in jewellery shops are in fact synthetics (ie real padparadsha sapphire, but man made, or lab created as the current euphemism puts it).I chose a synthetic sapphire to illustrate this article, partly because it had the most perfect version of the pad’s beautiful shade that I could find. All else aside, synthetics look more ‘perfect’ than natural stones. An old trade adage regarding the purchase of gems goes 'if it looks too good to be true, then it probably is…synthetic’. I want to put in a good word for man-made stones, they have a valid place in the market (though I must confess my personal collection is mostly rough untreated crystals). Not only are they affordable, they often look prettier than natural stones in jewellery. They also come without some of the negative association of natural gems, such as mining work conditions or pollution. They are also conflict free, and can be bought for cents a carat in any shape or size. If you want a suite of jewellery with huge rocks cheap, go synthetic.Natural or synthetic, treated or not, peachy padparadsha remains one of the most gorgeous shades in the mineral world.LozImage credit 10.04 carat antique cushion: ETSY.comhttp://www.gemselect.com/other-info/padparadscha-sapphire.phphttp://www.ajsgem.com/articles/natural-padparadscha-sapphire.htmlhttp://www.collectorfinejewelry.com/buyers_guide_padparadscha.htmhttp://www.palagems.com/ruby_sapphire_borders.htm -- source link

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