Sapphires- Gemstone of the Heavens
Note: This writeup was written by Kitten for kuro5hin. Used under permission
It is not difficult to see why sapphires are often called "the stone of the heavens". Their sparkling blue color evokes images of the sky, from the pale morning light of dawn to the crystalline azure of a cloudless midsummer day. Sapphires may also range from yellow, pink, orange, and even purple - all the glorious colors of the sky during a sunset.
These rare and radiant gemstones are more sought after than the diamond in many countries; sapphires being the preferred choice for engagement and wedding rings. If you would like to know more about these stunning gems, read on.
There are four primary means of judging the quality of any gemstone, up to and including sapphires. These criteria are commonly referred to as "The Four C's": Color, Clarity, Cut, and Carat weight.
There are three standards that are applied to determining the color of a sapphire. The hue - that is to say, the precise color (usually mapped on a color wheel) of the gem, is the first and most obvious. Is the sapphire a brilliant blue, a dignified violet, or a striking yellow?
Once the hue is determined, the saturation is established. This is merely an indication of the intensity of the color. A blue sapphire may be almost clear and achromatic, (low saturation) or a deep flourescence (high saturation).
The overall tone is important as well. This is an indication of the amount of light the stone absorbs. A matte white object would have a 0% tone while a matte black would be 100%. This is significant when choosing the sapphire that's right for you or your loved one, and although it depends on personal preference, keep in mind that the most saturated yellow sapphire will have a lower tone than a medium-saturated violet.
There are two primary considerations when determining the clarity of a sapphire. The visibility of inclusions (flaws) is the first and most noticible. A gemologist will consider the contrast of the inclusions against the color of the stone, as well as the location (are the inclusions in an inconspicuous place, such as near the edge or girdle, or are they directly under a facet?) Of course, the size and quantity of inclusions are taken into account as well.
Less obvious is the fact that inclusions are not merely cosmetic but may impact the sapphire's durability. The location of inclusions when determining durability is sometimes counter to the consideration of visibility. A crack near the edge of the stone will be less visible, but also increase the chance of breakage than one that is well protected inside the gem. A gemologist or appraiser will be able to determine the seriousness of any inclusions your sapphire may have.
The 'cut' of a sapphire is precisely what it sounds like - the shape that the gem has been cut into. This is likely the most subjective quality of a sapphire or any other gemstone, as it is almost entirely concerned with personal preference and asthetics.
The cut is evaluated according to the gem's shape, the style of the cut, how well it is proportioned, the overall symmetry, and of course, the finish.
Shape refers to the outline of the edge (or "girdle" in the industry), as viewed from directly above. The gem may be circular, oval, 'emerald-cut', heart-shaped, rectangular, triangular, or a number of other possible designs.
The facet pattern - cutting style, is also considered, but is also subjective. Certain facet patterns are more in vogue than others, but may also be more difficult or costly to produce. The standard cut (with a brilliant top or 'crown' and a heavily tapered lower half or 'pavillion') is the most popular for sapphires as well as rubies and emeralds.
Proportion and symmetry are very similar factors when it comes to determining the cut of your sapphire. Close attention is paid to how well-proportioned the gem is (ideally, the cut should maximize the brilliance of the stone) and the length-to-width ratio of the cut; stones that are too narrow or too wide are generally deemed unacceptable.
The symmetry of the cut should bear inspection as well. Do the facets match each other, and come to a well-defined point at their corners? Is the table facet (the flat part of the crown) well-centered? These details will be important when beholding and appreciating your sapphire for years to come.
The finish of the sapphire is the least important of all, as most finish issues - marks and scratches and so forth - can be corrected with a simple repolishing. Many gem dealers will repolish your sapphire free of charge, or for a nominal cost, so shop around.
Finally, the carat of the sapphire is establised. This is an unusual measurement system and has a complex history of evolution which is outside the scope of this document. For the purposes of this introduction to the world of sapphires, you need only understand that one carat is equal to five grams. However, a four carat stone may not be four times the price of a one carat stone. There is a psychological factor at work here, in seeing such large gems, and the cost increases proportionally - it is not a linear scale. It is impossible to establish a precise cost here, as the factors I have outlined above will play a crucial role as well; a one carat sapphire may be worth less than a .95 carat sapphire, if the smaller one is of a higher quality.
Polls suggest blue as the favored color of over 50% of the population, so it is no surprise that a striking blue sapphire is such a prized gemstone. It's gorgeous colors and remarkable transparacy are admired, but a sapphire is also second only to the diamond on the hardness scale, ensuring that your sapphire will be yours to enjoy for the rest of your life with the proper care - or an everlasting symbol of your love for the important person in your world.