Spinels | Gemstone Education

_{Red and Green Spinel Gemstones from Ceylon}

Education: SpinelSpinels are an interesting addition to the world of gemstones. Less well known than the top gemstones in the world, and even less so than the second group that is populated by less well known but relatively well-recognised category of semi-precious stone. Further, for many, the fact that are precious stones with this name is probably true. Before we get into the specifics of what spinels are, how they differ from other gemstones, and why they are valuable, as a starting point it is important to know that spinels are. Spinels, like most gemstones, are a type of mineral, which are valued for their hardness, durability and depending on the quality of the spinel, its colour. The name spinel is derived from the Latin word, ‘spina’ which means spine or thorn. Spinels for much of its history was confused with the popular corundum varieties, especially in relation to rubies which are found in similar mining environments.

Origins and Characteristics of Spinel Stones

The hardness of the spinel gem is measured on the Mohs scale for hardness, with the Spinel coming in a respectable 08. Just two behind the great diamond. The Mohs scale, for those who are wondering what it is about, is a scale where the numbers are rated based on the relative ease (or difficulty) of scratching a mineral with another. However one must bear in mind a single number does mean an incremental difference to the next. So a hard mineral-like spinel that comes in at 08 is much more scratch-resistant than a mineral that scores a 07 like quartz. However, given its position, the spinel gem is one of the harder minerals on the market. Spinels fall into the aluminium oxide mineral family, which is closely related to the corundum family. Spinel stones are found primarily in the metamorphic rock formation, and to a lesser extent in igneous and carbonate rocks. It is interestingly to note that the difference between spinel stones and rubies lies in the character of their formation. As both develop within the magma, and the varied mineral character in the environment determines the final character of the hardened stone. If the aluminium oxide is present at sufficient levels in the magma, and when combined with magnesium it will lead to the formation of spinel stones. This is one of the main reasons why spinel stones and rubies are often found together, and why for much history they were confused for being the same type of gemstones.

Top Countries for Spinel Gemstones

Whilst well noted for their rarity, spinel gemstones are found in a number of countries across the world. Whilst they are lower in abundance in terms of geographical dispersion than corundum based gemstones, spinels are found in countries like Sri Lanka (Ceylon), Tajikistan, and even parts of Africa notable for their sapphires: Madagascar and Tanzania. Based on the spinel gemstones in the market, the top country is Burma, a country that is noted for its strong resource strength in corundum based gemstones and has been able to produce a solid range of mineral oxide-based gemstones. The Burmese range of spinels has become so noteworthy that has spawned a distinct range of gemstone that has come to be identified by distinct colours that are understood to be specific to this South-East Asian nation. Another country that is noted for its range of spinel gemstones is the island nation of Sri Lanka (Ceylon). A nation, like Burma, which is noted for its red corundum variety, has come to hold a leading position in the market for vivid spinels.

Treatment of Spinels

The treatment of spinels is not a popular industry practice, unlike other gemstones where treatments are more popular, accepted and depending on the market, regulated. Some spinel might be subjected to colour altering heat treatment. The treatment is believed to remain stable under normal wearing conditions, however, this practice is well adopted unlike in the world of sapphires, buyers are advised to inquire into the history of their choice of spinels: in terms of type and extent of the gemstone treatment.

Popular Spinel Gem Colours

Whilst the colour is arguably the most important factor in gemstones. Spinels in their purest state are colourless. Similar to corundum based ones, the colour in spinels is the result of external elements, like chromium, and other types of metallic elements that give rise to the variety of colours in which they are found. Given their historical connection with rubies, spinels are generally valued for their beautiful red colours, which are found in an array of shades in a select range of colours. For in addition to the popular red, spinels are also found in blue, orange and even shades of pink. However one must understand that despite the similarity in colours generally, spinels differ in tone and intensity from sapphires, rubies and even garnets.

Blue Spinel

Blue spinels are highly popular in parts of Ceylon, where spinel stones in this particular hue predominate. The blue variety of spinel stones that come from this part world tend to range from a darker to lighter side, featuring a weaker colour intensity. The source of colour in spinels is due to the traces of iron (Fe) found in the stone Whilst the range of blue spinel gemstones might be larger, they tend to lack the vividity that is found in the corundum range. Notable here are the highly prized cobalt blue spinels, which are now being sourced to the nation of Vietnam. In the Luc Yen district in the north of the country, spinel gemstones have been found with higher levels of saturation, with fewer cobalt spinel types being unearthed in Ceylon (Sri Lanka). There is some confusion in the industry about whether the prominent cobalt blue spinel’s colour is the result of the presence of cobalt atoms in the mineral. However, what is clear is that the cobalt colour in this gemstone variety is highly sought after.

_{Red Spinel Gemstone from Ceylon}

Red Spinel

Long confused with rubies, red spinels are arguably the first entrants in the world of this gemstone variety. Red spinels which are found in parts of Burma, and more recently in Vietnam get their colour from the presence of the element chromium. Red spinels have become something of the hallmark of gemstones in this range, for depending on the vividity of the colour found in the stone these can even match the dominance of rubies or the subtle red hue of the garnet. Interestingly, like its corundum cousin spinels are also found in the pink. Pink spinels are interesting in that they are generally valued less than red spinels on average, however, certain rare types of pink spinels with good vividity tend to surpass red spinels in terms of price.

_{Green Spinel Gemstone from Ceylon}

^{Green Spinel Gemstone from Ceylon}

Red Spinel Gems Vs Rubies

In the world of gemstones, rubies have been the most dominant choice when it comes to gemstones with a natural red hue. Rubies that are part of the corundum family are valued for their rarity and beauty and the need for gemstones that manifest such qualities drove the search for them. Since Spinels have been in use for thousands of years, and for some time they were confused with rubies. Since both gemstones are similar in their mineral character, and even more interestingly these two mineral gemstones tend to be found together. And it wasn’t until the year 1783 when the French mineralogist Jean Baptiste Louis was able to determine the mineralogical difference between Spinel from the corundum based ruby.

^{Ruby, Spinel and Garnet colour comparison}

Needless to say, rubies are the top gemstones when it comes to those which feature a red hue. Combined with the historically lower supply of quality red spinels, corundum based gemstones have been the more popular choice. However things have started to change in recent times, one: with the wider recognition of spinels as a valuable addition to the gemstone range, and the increase in the supply of quality spinel gemstones from countries like Vietnam. Notably the red to orange coloured ones. Interestingly owing to the refractive character of spinels, the colour intensity in this particular gemstone can potentially outshine that of the ruby of the same hue. However, this needs to be balanced with the higher durability of ruby.

_{Purple Spinel from Ceylon}

_{Purple Spinel Gemstone from Ceylon}

The Most Famous Spinel: The Black Prince's Ruby

If one is to speak of the world’s most famous or well-known spinel, funnily it is a gemstone that is known as a ruby. The Black Prince’s Ruby is found in no place less than the Imperial State Crown of the Crown Jewels. If you have seen it, it is that huge red gemstone that stands at the centre of the Cross, whose origins goes back to the 14^th century, with the region of its origin being traced to Afghanistan-Tajikistan. This massive gemstone weighs an astounding 170 carat. A true Royal gem. And it is spinel, that was confused with a ruby. So the lesson for us possibly is that a quality spinel stone will make for a good ruby alternative.