For the month of October, we have two spectacular gemstones; opal and tourmaline.
The first birthstone, opal had its name derived from the Greek word opallios which means ‘to see a change in colour’. These stones are traditionally given on the 14th wedding anniversary. There are two types of opals. Opals that feature more than one colour of the rainbow, like the fire opal, are known as ‘precious opals,’ whereas those without the play-of-colour, like the black or white opal, are known as ‘common opals.’
There is a 3 to 21 percent water content in opal and combined with its hardness of 5.5to 6 on the Mohs scale, makes the gemstone rather delicate, and will crack under extreme temperatures, dehydration or direct light. So the safest solution is to clean it with warm soapy water and store it separately from other gemstones that are harder than opal.
As for the second birthstone, the tourmaline had its name derived from the Sinhalese word toramalli which means ‘stone with mixed colours,’ due to having more than one colour in a crystal. Among the most popular are the ‘pink’ and ‘red’ rubellites, the emerald green ‘chrome’ tourmalines, the ‘watermelon’ tourmalines, and the neon-green and blue-to-violet ‘paraiba’ tourmalines. These gemstones are to be given on the 8th wedding anniversary. Due to its vast range of colours, tourmalines are often mistaken for a variety of gemstones. An example would be the ‘Caesar’s Ruby’ pendant, which was later proven to be a red (rubellite) tourmaline in the 1800s.
Tourmaline gemstones are rated 7 to 7.5 on the Mohs scale of hardness, which make them suitable for everyday wear. These gems are usually stable enough to withstand light and most chemicals, but heat can be damaging. It is best to clean them with warm, soapy water and a soft brush. Ultrasonic and steam cleaners are not recommended. (Source: GIA; AGS)