Question
sapphires
I recently inherited about 400 rough montana sapphires found by my grandmother and great-grandmother near Phillipsburg, Montana. I am considering having some of them heat treated before cutting. Can you give me some idea of which stones (size, color, etc) are the best candidates for heat treating? Most of my stones are paler colors, and many are greenish, although I have plenty of blue tones, and also some pink, yellow, white, and darker aqua colored ones as well. They range in size up to about 10 carats. Light can be seen through most of them.
I also have about a dozen of these stones from 0.5 to 3 carats that have already been faceted. Can the faceted stones be heat treated? I had them appraised, and due to their paler colors and cloudiness, most of them appraised for under $100. I have attached an image of a few of these faceted stones. The larger dark blue one was heat treated before faceting.
Thanks for any information you might be able to share.
AnswerHello,
The treatment is good for all of them. Below is some information on this subject.
Montana Sapphires
Montana is home to some of the largest Sapphire deposits in the world.
Known as the "Native American Sapphire" Montana Sapphires are available in
every imaginable color of the rainbow. Montana Sapphires are considered
"Fancy" Sapphires, ( colors other than, but also including Blue ). Many experts rate
Montana Sapphires as "The Finest Sapphires in the World!"
Advances in sapphire heat treatment over the past two decades has opened the doors to competition. It is an established fact that 90 percent of all gem grade sapphire is heat-treated. Montana sapphire boasts a rainbow of colors when properly treated. It is also renowned for its high refractive index when properly cut and its ability to retain brilliance under a variety of lighting conditions.
This process improves the sapphires, both in color and clarity. The heating process does not use artificial coloring of any type, it simply causes a property change in the stone that dissolves an element called rutile, eliminating the cloudiness often seen in sapphires. The difference between natural and heated stones is dramatic. Some stones are left in their natural state, particularly if they are gem quality. Only about 3-5% of Montana Sapphires are gem quality as found.
An additional consideration when deciding whether to heat or not is the color of the stone. Occasionally a stone is such a spectacular color, that one has to decide whether or not to risk the possible color change that may occur as a result of heating. There is no way to know for sure what the end result will be, and sometimes the decision is made to leave the stone in its natural state in order to retain the color.
Of the four Montana sapphire regions, only Rock Creek (just outside Philipsburg)
Is known for its variety of distinctly crisp and sharp colors. As tastes have shifted to more brilliant gem jewelry, Rock Creek sapphires have come into their own. Particularly with the advent of readily available heat treating.
Rock Creek sapphires are able to fill a niche worldwide. Colors range from the classic "cornflower blue" to "red-orange" and "mint green." The colorful variety of sapphires found and finished here have a character and beauty all their own.
One of the most popular attractions of the Philipsburg area is the sapphire mining offered to the public. It is pretty unusual that people are able to dig through gravel in search of rare, fine gems, but that is just what is offered in Philipsburg.
Year round, sapphire gravel is available for washing, and then if you please, you can watch the sapphires get heat treated and prepared for jewelry. There are several places in Philipsburg where you can find these precious gems. However, the Sapphire Gallery has the only heat treatment facility open to the public.
Other Montana sapphire localities are located on the Missouri River about 15 miles NE of Helena. If you look at a Highway map you will see Canyon Ferry Dam east of Helena, and just to the west of it is Hauser Lake. Spokane Bar is on the south side, west of the Dam and Eldorado Bar is NW of that on the north side of the lake/river.
Hope this helps you,
Steven D.Covey
