December has three gemstones –turquoise, zircon and tanzanite. I am going to talk about the first gemstone in this post and deal with zircon in a following post.
Turquoise is a beautiful ornamental stone which has been used in jewellery for centuries. The Egyptians used it a lot, with discoveries of jewellery set with turquoise from as early as 3000BC. King Tutankhamen’s funeral mask from about 1323 BC was inlaid with turquoise. The name ‘turquoise’ arose in the 17th century, derived from the French expression ‘pierre tourques’ (‘Turkish stone’) as it arrived in Europe via Turkey, mainly from mines in what was then Persia where it was mined for over 2000 years. Iran and Egypt still operate mines today.
Turquoise was also found in early jewellery in Mexico, the US and China. Jewellery dating from around 300AD has been found in Arizona. In 1576, the conquistador Bernal Diaz del Casillo noted that the Aztecs of Mexico valued a blue stone called chalchihuitl.
Turquoise is described as a blue stone but its colour can vary a lot, from sky blue to a greenish blue, depending on two factors. The first is where it was mined. Typtically found in arid regions, turquoise is formed when acidic watery solutions seep into rocks and fill crevices. It is often interwoven within a matrix of the host rock. This matrix can be hard to spot, like a spider web in some instances or it can be a striking feature of the stone. Persian turquoise is a sky blue, usually a uniform colour, without markings. Some turquoise from the Americas can have be a greenish colour as it contains iron. Turquoise from Bisbee, Arizona contains dark veining or spider webbing matrix. The turquoise in the pendant below is likely to be from Bisbee.
The second factor is how often as well as the manner in which turquoise jewellery has been worn. It is very porous and so can darken and turn greener due to perspiration and access to water. Sometimes, particularly if the jewellery is worn close to the skin, the colour of some pieces can become a dark green.
In Georgian and Victorian times, turquoise was used a lot in sentimental jewellery containing flowers as the colour was similar to the blue forget-me-not flower. The pendant in the photo at the top of the post is a good example of such jewellery. There are some lovely Victorian brooches in the shape of a bow or knot that contain turquoise beads. Generally, antique English and European turquoise jewellery will be set in gold and is often pavé set, that is, small beads or stones set closely together, as in the photo above.