Spinel is a gemstone, that is unique thanks to its variety of colors; the most known of them is a deep-red, however, very deep-red stones are not suitable for jewelry purposes, therefore, the transparent ones, are most valuable, due to their similarity with the Ruby.
The Difference between Spinel, Ruby and other gems
The ancients couldn’t determine a difference between the Spinel and the Ruby, therefore, there are too many mentions concerning the Spinels of immense size, especially in the Middle Ages.
However, Mr. De Lisle has discovered the distinction between these two gems in 1783, thus he was the first who managed to distinguish them. So, until this date, many Spinels have been sold as the Rubies. Such instructive example, can be demonstrated in the case of the Royal Crown of England.
Indeed, it is too hard to distinguish these gemstones at a glance. However, nowadays we know how to do that:
The hardness of Spinel is 7,5-8,0/10
The hardness of Ruby is 9/10
Specific gravity of Ruby is 3,9-4,16
Specific gravity of Spinel is 3,5-3,6
Spinel is also distinct from Ruby, due to different form of crystallization.
It is also very important to distinguish Spinel from Garnet. The crystals of Garnet are fusible, whereas the crystals of Spinel are infusible. Dichroism is a principal feature to distinguish Spinel from colored Topaz. Topaz also became electric, when heated.
Ancient Indians called Spinel “Lai Eumani,” however, it derived its modern name probably from Latin word meant “spark,” thanks to the form of Spinel’s crystals.
By the way, there were many opinions in regards to the origin of the name “Balas” (most known variety of Spinel). Thus, Marco Polo stated, that it derived from the name of the mount Baluchani in Pegu.
The first specimens of Spinel were supplied from India. It is mentioned that the King of Oude possessed a huge specimen of blue spinel. This specimen was about the pigeon’s egg size and possessed splendid brilliance. Furthermore, there are the evidences, that there were two stones, delivered in the UK in 1861, which weight was 102,25 carats and 187 carats, respectively.
Such most popular varieties of Spinel as “Spinel Ruby” and “Balas Ruby” were discovered between Afghanistan and Tajikistan, in the region known as Badakhshan. The locals believed that these two stones are always mined together.
Varieties of Spinel
There are several varieties of Spinel:
- Spinel ruby
- Balas or balais ruby
- Almandine ruby
Colors of Spinel
In spite of commonly known red Spinel, there are many other tints of this gemstone, such as:
- Deep red for Spinel Ruby
- Rose red for Balas Ruby from Czech Republic
- Violet for Almandine Ruby
- Orange red for Rubicelle Ruby
- Black for the rare variety called Pleonaste
- Green for Russian Spinel (Ural Mountains)
- Blue for the specimens from Sweden
The specimens of Spinel suitable for jewelry purposes are chiefly obtained from Sri Lanka, Thailand, Myanmar as well as from Czech Republic, Austria and United States (principally in New Jersey). There are also Spinel mines in Russia and Sweden.
There is a known method to obtain synthetic spinel by heating together alumina, magnesia, and boracic acid. This method was known since the XVIII century.
Credits for image to: Géry Parent