If you have been shopping for sapphires you will come across stones which are either natural or have been enhanced by heat or other methods. Here, we will discuss the difference between natural (no heat) and heat treated sapphires. The application of heat treatment to improve the color of sapphires dates back many centuries and has been widely accepted in the global market for its affordability and the stability of treatment. Whereas heat treated sapphires have made it possible to reach store shelves on every corner of the world, natural unheated sapphires are still highly sought-after for their natural beauty, rarity, and value as they require a perfect balance of nature's forces.
Before we go further and you make a decision on which type of sapphire you prefer it is important we cover basic gemology: quickly, all sapphires are a variety of the mineral Corundum, which is simply Aluminum Oxide. Other members of the corundum family include ruby, padparadscha, star sapphire, and many other colors of sapphires. What this means is that all these stones have the same basic composition.
So then, what gives sapphires its blue color? Trace Elements. The blue color in sapphires is attributed to the type and amount of Titanium and Iron present in the corundum crystal. The right balance of Titanium, Iron, with Aluminum Oxide will result in a blue sapphire.
Are natural, no-heat sapphires more rare and valuable? Yes, sapphires which have not undergone any enhancement by man are in their natural state and far more rare and valuable than heated sapphires.
Are all unheated sapphires the same? No. Every unheated sapphire is different and each one's uniqueness is attributed to the environment in which the crystal was formed inside the earth.
Why do unheated gem quality sapphires command high prices? Fine quality blue sapphires are extremely rare and sought-after by collectors worldwide. For a sapphire to be considered gem quality it must posses a beautiful saturation of blue, have minute to no eye-visible inclusions, cut perfectly for maximum brilliance, be a lustrous crystal in which the wearer's eyes can swim, and must not be enhanced by any treatment. Simply put, it has to be the perfect balance of nature's ingredients, a cutter's artistry, a jeweler's craftsmanship, and the wearer's wondrous eyes.
Why heat sapphires? To improve the color. Someone in the supply chain felt these preheated stones lack the desirable blue and could command higher prices if the color improves. Stones which do not have the ideal type or amount of trace elements will not have a strong saturation of blue and will therefore undergo heat treatment for improvement.
After heating a sapphire, is the color permanent? Yes - this is a boon for heated sapphires and the reason why the treatment is accepted worldwide. The color of a heat treated sapphire will remain the same and will not wear off, unless the stone is treated again.
Are all heated sapphires the same? No. You will find that if you put two heated sapphires next to each other they will most likely look different in the shade of blue. The process of heat treatment is not perfect and only improves the color under ideal conditions with the correct placement and amount of trace elements in the crystal.
Are heated sapphires undesirable? No, but they lack the natural feel of unheated sapphires. The important factors for any color gemstone is that it radiates a beautiful color, clarity, cut, and crystal.
Which is a better investment? Generally speaking, sapphires of vivid/royal blue color and fine clarity which have not undergone any treatment are the ideal investment, however, there are antique and signed pieces by famous houses which have incorporated heat-treated sapphires. These pieces hold special value because of their history, provenance, originality, design, period, etc, and not so much for the quality and treatment of the sapphires. Fine quality natural sapphires are becoming increasingly rare and have shown a substantial increase in market value over the last five years. Fine quality, sapphires which have been treated by heat have also increased in price due to demand but not significantly.
By appearance, is there a difference between natural and heat treated sapphires? No. From a distance or without gemological experience it is difficult to state whether a sapphire has been heated. However, a natural no-heat sapphire will have a softer and smoother surface appeal.
How will I know if a sapphire is natural or heated? This scientific assessment can only be done by a highly experienced gemologist and more convincingly by a reputable laboratory such as GIA, AGL, Gubelin, SSEF, or GRS who have years of research data, high-tech equipment and experienced gemologists analyzing their findings. If you are looking to purchase a sapphire be sure to request for a certificate from any of these reputable laboratories.
Write to us if you have any more questions regarding heat and no heat sapphires.