4th Wedding anniversary (Blue Topaz) and 23rd Wedding anniversary (Imperial Topaz) gifts
Until the late 1960’s, most topaz seen in jewellers windows was yellow – brown in colour but treatment experiments in the early 1970s meant that the method of producing blue topaz increased and a variety of shades of blue suddenly became readily available.
In its pure chemical form, topaz is colourless and, as such, it is known as an ‘allochromatic’ gemstone which means that it gets its colour from added impurities in its chemical composition during the crystal growth. Depending on the impurity different colours were found.
The pink, red and violet to purple topaz that are mined have had some chromium present at the time the crystals formed. Yellow, browns and naturally occurring but extremely rare blue topaz have had their colour caused by atomic imperfections
It is the widely found colourless topaz that is treated to produce the vast majority of the blue topaz seen for sale today. The colourless stones are subjected to irradiation and heat treatment which produced a stable blue colour that does not fade. As this process is a permanent change it is one that is accepted within the trade and does not have to be declared at the point of sale.
In contrast to the permanency of the change of colour to blue, you may see a material marketed as ‘Mystic Topaz’. This is, in fact, colourless topaz which has been subjected to a PVD (Physical Vapor Deposition) Coating – a microscopic layer of a metallic oxide compound. With this just being a coating, it is NOT a permanent feature and should be disclosed to the buyer as this coating can be damaged either by day to day wear or by the polishing machines in a workshop.
Topaz has a hardness (resistance to scratching) of 8 on Moh’s scale, making it seemingly good for all types of jewellery, however, it does have direction of perfect cleavage meaning it can break along certain planes of symmetry if given a hard knock. We would always recommend that any gem-set jewellery is removed before commencing any rough work.
Most gem quality topaz is fairly free from inclusions, but, sometimes, both solid and/or liquid filled inclusions occur. When cleaning your topaz jewellery just use soapy water and a soft brush. DO NOT subject the gemstone to an ultrasonic cleaner or steam cleaner as they could cause the topaz to crack.
Topaz is mined in Minas Gerais in Brazil and this mining has been carried our for over 200 years. Colours found in this area include yellow-orange, red, pink and violet blending with red, orange or purple..
Another source for pink topaz is in North West Pakistan, Ghunao Hill, near the small town of Katlang. This area is renowned for pink topaz and it has been mined here since 1972.
Other localities where topaz can be found are Namibia, Mexico, Nigeria, Madagascar, Myanmar (formerly Burma), Sri Lanka (formerly Ceylon), the USA and Russia.
“Imperial Topaz” is an intense golden to reddish-orange colour and was found, historically, in Russia in the 19th century. It was given its name to honour the Czar. In these times, the gem could only be owned by members of the Royal Family. Today, imperial topaz is found mainly in Brazil, in Ouro Preto.
“Sherry Topaz” is named after the sherry wine and is a yellowish brown or brownish yellow to orange. This photograph is of a particularly fine example, which we currently have in stock.
