When purchasing gemstones in jewellery, such as Sapphire Rings, Sapphire Pendants and Sapphire Earrings, then the 4 C's of colour, clarity, carat and cut become relevant, with colour being first.
Corundum in its earth state is colourless, often called white, and although rare, tends to not be expensive because it does not show much brilliance.
The colour that is present in gemstones is down to the amount of trace elements in the form of metal oxides that are present in the stone as impurities. Titanium oxide is the element that brings about the blue hues, ferric oxide is for yellows and chromium oxides give the colour red as in the gemstone ruby.
Sapphires although found mainly in shades of blue, are also available in many other shades such as pink, yellow, orange, green and purple. These are known as fancy coloured sapphires. A pink/orange version is also found and called Padparadscha and are very collectable.
Pink Sapphires - these are available in all shades of pink and range from deep luxuriant rose (sometimes mistaken for ruby) down to bright "hot" pink hues. These are usually sought after and valuable compared to most of the other blues.
Yellow Sapphire - these are found in shades of dark yellow and light yellow (canary yellows).
Green Sapphires - found in light green shades similar to peridot, through to much darker emerald shades, but are usually the least desirable of colours.
Purple sapphires - middle of the road in value and show a great colour scheme.
Star Sapphires - although found in all shades of blue, they are famed for their unique 6-star effect, known as "asterism".
Colour Change Sapphire - these will change their shade of colour depending upon the light. This is known as "pleochroism" and is also prevalent in such as tanzanite gems.
Cornflower Blue - Cornflower Blue is often cited as the best colour and most desirable to purchase.
Ceylon Blue - these are sapphires in the pale to middle blue shades. Unless the stone is known to be from Sri Lanka, it would be called "Ceylon-type".
Australian Blue - the majority of dark sapphires come from Australia, and the term "Australia Sapphire" is most often used to refer to dark-coloured sapphires.
Padparadscha - possibly the most expensive of the sapphires available to purchase today. They are found in quite unique pink-orange tones.
It is obvious (to most!) that you should really set your mind to a budget and then keep to it. Buy what you like, not what you are supposed to like!
Just because historically cornflower blue is said to be the most desirable, if you want a darker shade of blue Australia, these are for you. Buy what you really want, not what you are told..,
I sincerely hope you have found this short article interesting, and it may be of some use for you in the future.