Are Montana Sapphire Heated

     The answer is technically no because “all” of the sapphires mined in Montana are not heated. However, it is a fact that “nearly” all Montana sapphires are heated. If the form of the question were “Are Montana sapphires heat treated?” the answer would be yes.  The answer would also be yes if the question were, “Are virtually all of the Sapphires from Montana heated?”  A consensus about the ratio of unheated to heat is in the vicinity of 1/10. 

     Many concerns drive this question.  People may feel that the sapphire has been corrupted in some way if treated by heating.  Others may think that it is no longer natural.  Some may wonder if the benefits of heating will diminish over time or cause the stone to lose value.  The answer to both of these questions is a definite no.

     The purpose of this article is not only to answer the fundamental question but also to provide additional information associated with this critical topic.  Hopefully, some of the comments that follow will be helpful to many of the people who are interested in this issue.

History of Developing Effective Heating Methods

      It may be helpful to describe some of the history connected to the heating of sapphires. Sapphires have been heated for hundreds of years in most places worldwide, wherever they have been mined.  Methods improved over time through trial and error—the technology seldom, if ever, advanced beyond charcoal fires. 

     Unfortunately, the skills learned to heat sapphires from other parts of the world did not work well when applied to Montana sapphires’ heating. This was unsurprising because sapphires mined in different localities often have slightly different trace chemical compositions. Minor differences in the trace chemistry within gemstones call for other heating protocols.  Sapphires mined in Montana are no exception to this general rule.

Rock Creek Montana Sapphire before and after heat treatement
Montana Sapphire before and after heat treatment

     The history of developing effective heating methods for Montana sapphire is different and somewhat unique compared to the history described above. First, the learning curve for heating Montana sapphire, unlike elsewhere, is a modern phenomenon.  Gas and electric furnaces have replaced the traditional reliance on charcoal fires.  Second, the development of the best heating protocols has been assisted by scientific instruments that provide more information about what chemical reactions occur within the stone as it is being heated.  Effective heating procedures for sapphires mined in Montana have only been developed within the past thirty to forty years.

     It should also be noted that despite the scientific and technological tools used to discover the best treatment protocols, not all Montana sapphires benefit from heat treatment.  Some have not improved at all.  Others may be improved very slightly.  The results are very uneven, but there is always a continuum of good or excellent improvement to no improvement whatsoever. 

Predictions as to which sapphires will improve could be more reliable.

Are Montana sapphires heat-treated to create value?

Heated montana sapphire
Heated Rock Creek Montana sapphire

     The next question to consider is what benefits can be achieved from heating. Color and clarity can theoretically be improved, which is what is hoped for from any given heat treatment regime.  Not all inclusions can be minimized by heat treatment, but some can, and again, as mentioned above, the extent to which they are minimized varies from large to small.

     Not every color of Montana sapphire can be changed by heating.  A good example is pink.  The element chromium can cause some sapphire to have a pinkish appearance.  Chromium is unaffected by heat application, so pink cannot generally be created or enhanced by heating. 

     The most common changes involve changing the tone of existing hues like yellow, green, and blue.  These colors can be made lighter or darker.  Green hues can become more visibly bluish.  Again, changes can occasionally be dramatic, but most often are on a continuum from some change to no change. 

     It is imperative to realize that not all heat treatments are the same.  Sapphires can be simply heated.  In other instances, elements can also be added to the sapphires during heating to improve the results.  An example of this would be the addition of beryllium. 

     Whatever has been done to the sapphire, including simple heat treatment, must, by law, be disclosed to the consumer.  This is very important because some consumers might not object to simple heat treatment but would object to purchasing a stone with added elements during the heating process.  Objects could be aesthetic, or they could involve concerns about value. Regardless of the reasons, disclosure is imperative.

Sapphire Heat Treatment Effects on Value

     Are Montana sapphires heated to increase value or marketability?  This is a vital question that interests many people and should also be discussed.  It is true that given two stones that are alike in every respect ( a practical impossibility), the unheated stone will cost more than the heated stone.  How much more is a much-debated topic because other variables like rarity may be involved.  Also, it is most often true that if a sapphire looks better because it was heated,  it will cost more than if that same sapphire was sold as unheated.  Unfortunately, any answers more definite than the above would be suspect and justifiably so. 

     The public has, for the most part, like the trade, accepted the reality that most Montana sapphires are heat treated like sapphires everywhere else in the world are to improve their appearance.  This importance probably stems from the fact that heat treatment, for the most part, duplicates the natural processes involved in gem formation, adds to the abundance, quality, and variety of fine gemstones in the marketplace, and tends, therefore, to reduce the overall costs to the consumer.

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