Sapphires – the Gemstone for a Princess

Sapphire is an aluminum oxide mineral known as corundum that is so hard that it resists nature’s efforts to erode it. It is one of a handful of gemstones of this structure (which also includes ruby) and as a result can be found in sediment where softer stones may wear. It is a gemstone found on many continents of the World with its value dependent on the gemstone’s size, color and clarity. Blue sapphires, especially those with the “cornflower” blue, tend to be among the most valuable in terms of color, with one of the best (and largest) examples ever discovered available for your viewing pleasure in Washington DC; the Logan Sapphire which is on display in the National Museum of Natural History is 423 carats (83 grams for those thinking in  the metric  scale). Note however that this is a ‘faceted’ sapphire (similar to those found on this page). You also find large sapphires (including star sapphires) in ‘cabochon’ form – which are shaped and polished stones instead of faceted. These can be even larger than the Logan sapphire. For example, the Star of India (a stone that actually originated in Sri Lanka)  is actually 563 carats, and is considered the world’s largest gem-quality blue star sapphire.

Sapphires come in a range of colors – basically any gem-quality corundum that is not red known as a sapphire (this includes white sapphires that are sometimes confused with diamonds) – with the default expectation being a blue stone. The gemstone derives its color from impurities such as iron, titanium or chromium.  Based on the extent and nature of the impurity drives the specific color. Those sapphires of blue with an element of violet are regarded as fine quality all other things being equal. If the secondary color has a greenish tinge that is generally  regarded as less than ideal. Blue is said to be the most popular color on the planet and the depth of blue found in a sapphire makes it a real find….However, whilst it is mostly famous for its blue color, several other colors are fairly common, green, yellow and pink and there are some rare stones which can appear to change color in different light. Such rare beauties with that pleochromatic property are best handled by expert and skilled cutters have the skill to be able to see the best way to cut a particular stone to bring out the color change.

The quality and color of Sapphires can vary enormously and one element of value can be the region it came from.  Today, Sapphires are mined in Australia which is the largest producer of Sapphire by volume, as well as in East Africa, Madagascar, Myanmar, Thailand and Sri Lanka. In Australia, there are mostly found in New South Wales and Queensland. Myanmar has a set of famous mines in the Mogok region, and in Thailand there are sapphire deposits in Chantaburi and Kachanaburi. Sapphires from Sri Lanka are mostly from the Ratnapura district. The best deposits in the USA are in Montana, especially those known as Yogo Sapphires. There are also gorgeous blue stones found in Kashmir – though these are difficult to source given political issues in that location.Synthetic sapphire is made on a fairly large scale, about 250 tons annually mostly in the USA and Russia. It has none of the impurities of the natural gemstone which is one way of distinguishing between natural and synthetic sapphires – click here to learn more about the differences between synthetic and natural stones.

Color                                                     Various except ruby red.Crystal                                                  Trigonal

Mohs                                                    9

Specific gravity                                  3.95 – 4.03

As already stated Sapphire is extremely hard so it has uses far beyond the decorative. The uses included industrial use for solid state electronics and optical components, scientific instruments, wrist watch crystals and movement bearings. Synthetic production means there is never a shortage of raw material for industry.

However, the sapphire is a prized and valuable gemstone for jewelry and its hardness means that it is extremely difficult to damage.  Given their structure, Gem cutters tend to shape them into ovals or cushions to preserve as much of the original stone as possible. Those that are made into round shapes involve removing a good deal of the rough sapphire at the later stages in the cut and hence they are more expensive than the oval or cushion.