October Birthstones; Tourmaline and Opal

October Birthstones; Tourmaline and Opal

At Roseanna Croft Jewellery we love birthstones! Gemstones filled with sentiment that can mean so much to one individual, just because of the month you were born in! And if you were lucky enough to have been in the Autumnal month of October, you have two to choose from!


The name “tourmaline” comes from the Sinhalese words tura mali, which mean “stone of mixed colours.” As the name says, Tourmaline is different from other gemstones as it has a varied spectrum of colours in all shades of the rainbow.  It isn’t one mineral, but a complex group of minerals, all with different chemical compositions and properties.  Certain elements produce certain colours, and a lot of these resulting varieties have their own names.    

Black Tourmaline, or ‘schorl’ is rich in iron which gives it a dark hue from deep brown to blue/black, and, and although much of it isn’t gemstone quality, it makes up 95% of all Tourmaline.  Dravite (brown Tourmaline) is rich in magnesium, making it range in colour from yellow to brown, and is found in Slovenia.  Elbaite, containing lithium traces, offers the widest range of gem quality Tourmaline colours, as the lithium combines with other colour elements.   These are just a few of the many varieties and colours of Tourmaline, which is mined in Brazil, Sri Lanka, Nigeria, Mozambique, Madagascar, Afghanistan, Pakistan and the U.S.—primarily Maine and California.

Due to the choice in colour options, and the fact that Tourmaline is fairly hardwearing (with a score of 7-7.5 on the Mohs scale), it makes very popular and hard wearing birthstone jewellery.  One of its most impressive traits is its ability to become electrically charged through heat and electricity, at which point it can act as a magnet by oscillating and by attracting or repelling dust particles.



The name Opal originates from the Greek work ‘opallios’, which means “to see a change in colour”.   This ‘play of colour’ was explained in the 1960’s, when scientists discovered that some Opals are composed of microscopic silica spheres that diffract light to display different colours of the rainbow.  These are known as ‘precious Opals’ whereas the ones without this play of colour are known as ‘common Opals’.

Unlike Tourmaline, there are few different varieties of Opal in existence, and only a few of these (like Fire Opal and Boulder Opal) are recognised.  They are often referred to by their main colour or ‘body colour’ – black or white.  Opal’s classic country of origin is Australia, where seasonal rains soak the parched Outback and carry silica deposits into cracks between layers of rock.  When the water evaporates, these deposits form Opal. 

With a hardness of only 5.5 to 6 on the Mohs scale, Opal is a fairly delicate gemstone, but is well worth the extra care if choosing it for jewellery as for centuries it has been associated with good luck. 

If you’d like to read more about October birthstones or find your own birthstone, please download our factsheet below.  And if you would love to own or gift someone a piece of birthstone jewellery, please don’t hesitate to get in touch. 

Love, Roseanna & Co x