When seeking a fine sapphire, the collector-connoisseur is advised to avoid labels and look at the gem on offer. Ceylon sapphire has its own distinct and beautiful look; the natural color stones often have a bit more of a purple secondary hue.

New contenders from Africa

The Tunduru deposit has been described as the most important discovery in fifty years. Tunduru is in southeastern Tanzania hard against the Mozambique border. The best of the Tunduru stones have a deep royal blue color similar to Ceylon; however, in the words of Joseph Belmont, a dealer noted for his fine eye, “Tunduru stones have a much better crystal.”136 The best of Tunduru stones are a step up from Ceylon sapphire and only a half step down from fine Burmese sapphire.

The politics of Tanzania make for sporadic production. Small amounts of Tunduru rough are still finding their way to market in Nairobi. In addition, a few “brilliant blue” stones are to be found in parcels coming into Nairobi from Rwanda and occasionally from Lodwar in northern Kenya.

At this writing blue sapphire from Madagascar is making a major impact on the market. These stones closely resemble Ceylon sapphire with perhaps a bit more of the purple secondary hue.

Australia remains a steady supplier of blue sapphire to the world market. Sapphire is found at a number of sources in Queensland and New South Wales. For many years Australian stones had the reputation of being greenish and overdark with tonal values of ninety percent or more. Sapphire, like ruby, emerald, and tsavorite garnet, is judged by the purity of its primary hue. A little violet is desirable, but green is the bane of blue sapphire. Thai dealers often bought the best of the Australian stones, heated them, and sold them labeled Ceylon in the Bangkok market — and still do. However, with new sources and advanced heating technology, a larger quantity of finer color stones are available today than in the recent past.

America the beautiful

Alluvial sapphire deposits were first discovered in Montana’s Missouri River in 1865. Three other sites — Dry Cottonwood Creek, Rock Creek, and Yogo Gulch — were added before the turn of the century. Yogo Gulch, the only hard-rock deposit, was mined steadily until the late 1920s, when it was abandoned; production resumed in the 1980s.

Yogo sapphire is often described as “cornflower” blue, a rich purplish blue hue that has been erroneously compared to Kashmir. Generally, the finest of the Yogo stones have a distinctively crisp “steely” (slightly grayish) appearance. This steely quality is the result of a slight gray mask. These Montana beauties are of uniform color, relatively free of inclusions, and are not heat enhanced. Unfortunately, rough Yogo sapphire occurs in flat tabular crystals and rarely yields faceted stones in sizes above one carat. Seventy-five percent of current production consists of cut stones under one carat.

Sapphire from the three other sources mentioned has been of little commercial importance until recently. Although huge quantities of sapphire have been taken from the Missouri River and both Rock and Dry Cottonwood creeks, these areas produced mostly colorless to pale-toned (twenty to thirty percent) stones of little beauty. Advanced heat treating technology has significantly altered the situation. These techniques have raised rough yields from Rock Creek from as little as eight percent to as much as eighty percent facet-grade gem material.

The best of these blue sapphires display a rich (eighty to eighty-five percent) blue primary hue, with a pinch (five percent) of violet and a slight (ten to fifteen percent) gray to gray green modifier. Due to the apparent green secondary hue, Montana stones from these sources never approach the finest sapphire qualities. Blue Rock Creek sapphire most resembles high-grade commercial quality stones from Australia.