The Difference Between Unheated and Heated Sapphires
Blog, Education & Editorials

The difference between Unheated and Heated Sapphires

Anyone shopping for sapphires or any other gemstone is likely to come across natural stones or heated stone.  In the history of treatment of sapphires, the process of applying heat treatment to improve the color of sapphires was used many centuries back and has been used across the globe because the treatment is affordable and stable.  While heated sapphires have been available in the shelves of stores across the globe, Unheated sapphires are still attractive because of their beauty, rarity and value.

Before going further and making a decision on your preferred sapphires, it is significant to understand basic gemology: On a quick note, every sapphire consist of the mineral Corundum, which is basically Aluminum Oxide. The corundum family is also composed of components such as ruby, padparadscha, star sapphire, and a variety of sapphire colors. It is important to note that the sapphire stones are made up of similar basic composition.

What causes the blue color in sapphires?

Trace elements. The type and amount of Titanium and Iron in corundum crystal can be linked to the blue color in sapphires. The right balance of Titanium, Iron, with Aluminum Oxide will lead to blue sapphire.

Is it rare to find natural unheated sapphire, and are they more valuable?

Yes, sapphires that have not been taken through the treatment process exist in their natural state and are rarer and more valuable than sapphires that have been heat treated.

Are all unheated sapphires the same?

No. Every sapphire that has not been heated exhibit differences and unique nature that that is attributed to the surrounding environment where the crystal was unheated sapphire is different and each one’s uniqueness is attributed to the environment in which the crystal was made in the earth crust.

Why do unheated sapphires command high prices? 

Fine quality unheated sapphies are rare and have a high demand in the global market. The sapphires are also cut perfectly to achieve a brilliant color.  Be a lustrous crystal in which the wearer’s eyes can swim, and must not be enhanced by any treatment. In simple terms, a sapphire ought to be a perfect balance of ingredients of nature, artistry of the cutter, craftsmanship of the jeweler, and the wondrous eyes of the wearer.

Why are sapphires heated?

Heating of sapphires is meant to improve their color, remove color zoning, and improve clarity. There are people in the supply chain who feel that stones that are preheated do not have the desired blue color and could fetch higher prices upon an improvement to their color. Stones with no ideal type or quantity of trace elements may not attain a strong blue saturation; thus, they will be put through heat treatment to be improved.

Does the achieved color of heated sapphire become permanent?

Yes, heated sapphires have the advantage of achieving a permanent color, and this one reason why heated sapphires are widely accepted across the world. Heated sapphires’ color will remain the same and will not fade away.

Are all heated sapphires similar?

No. Two sapphires put next to each other will most definitely have a different appearance of blue. Heat treatment process may not be accurate and only achieves a perfect color under conditions that are ideal with the correct placement and quantity of trace elements in the crystal.

Are sapphires that have been heated undesirable?

No, but they do not possess the natural feel of unheated sapphires.  The significant factors for any sapphire to achieve a perfect look are that it has a radiation of beautiful color, clarity, cut, and crystal.

Is there a better investment?

Generally talking, an ideal investment is to buy an unheated sapphire which has vivid/royal blue color and fine clarity. Nonetheless, some heat-treated sapphires have are incorporated with antique and signed pieces by famous houses. The pieces are valuable because of their history, provenance, originality, design, and period, among others. The value of the pieces is not attributed to the quality and treatment of the sapphires. Natural sapphires of fine quality have become increasingly rare and have had a high demand in the market in the past five years. Sapphires of fine quality that have undergone heat treatment also have high prices because of the significant high demand.

Investments – Unheated Sapphire (Ceylon / Sri Lankan Sapphire has more value and demand in the market).

Engagement Ring – Heated / Unheated Sapphire

Casual Wear / Fashion Item – Heated

Astrology – Unheated

Is there a difference between natural and heat treated sapphires based on appearance?

No. Without gemological experience it is difficult to make assertions whether or not a sapphire has undergone heating. Conversely, a natural sapphire that has not gone through heating is bound to achieve a softer and smoother appeal on the surface.

How is it possible to identify a sapphire that has been heated and one that is natural?

It is possible to differentiate between sapphires that have been heated from natural sapphires with the help of a highly experienced gemologist who will carry out scientific assessment. The assessment will also be done more convincingly by laboratories that are reputable including GIA, AGL, Gubelin, SSEF, RGL or GRS. The laboratories have experience in data research, use high-tech equipment and gemologists who are experienced to carry out a perfect analysis of their findings.  Anybody looking to buy a sapphire must be sure to request for a certificate from the laboratories that are highly reputable.