Cut and uncut Yogo Sapphires In the late 1800's, Jake Hoover was mining for gold on Yogo Creek. He found pretty blue pebbles in his gold sluice box. Thinking that they might have some value, Jake sent a cigar box of them to Tiffany and Company for identification. They told him that his blue pebbles were indeed high quality sapphires. It turned out that these Yogo sapphires had more value than the gold that Jake had sought. Jake never made his fortune from his discovery, but a fortune in the sapphires would be mined until the mines close in 2004. Color range of Yogo Sapphires More rare than diamonds, the Yogo sapphires today rank among the finest natural sapphires in the world. Yogo sapphires are found in a remote Montana location. In Montana, known as The Treasure State, the sapphire is the state gemstone. The Yogo sapphire is one of the world's only natural and totally untreated sapphires. They were formed deep in the earth. Never needing to be enhanced in any way, the Yogo sapphire is truly rare. Yogo sapphires do come in a range of colors, from finest blue to violet. All of the colors of Yogo are totally natural. This gem is also of premium internal clarity, almost always being nearly flawless. Don sorting untreated yogo sapphires Yogo sapphires are totally natural and untreated. They have excellent color and clarity. Unfortunately, Yogo sapphires are usually found in smaller sizes. The crystals tend to be shallow and under one carat in rough weight. When these stones are cut to correct proportions they cut into finished stones of very small sizes. Well-cut Yogo's weighing over one carat are rare. Gems over two carats are extremely rare. Yogo sapphires are greatly prized for their beauty and rarity. The value of larger Yogo's is greater than other sapphires found in Montana. Very fine Yogo rough Average cutable Yogo rough Sapphires are also found in Montana in three other major areas. Missouri River near Helena, Rock Creek in the Sapphire Mountains, and Dry Cottonwood near Deer Lodge. These sapphires vary greatly from the Yogo sapphire. Montana offers more variety of colors in sapphire than any other locality in the world. Missouri River area yields sapphires of the largest size for Montana. Cut stones from here up to ten carats are found but are rare. Some gems over twenty carats do occur. These gems are found in a more light steely-blue color to a blue/green color. Heat treating of these stones removes undesirable cloudiness (silk) from the gem and sometimes improves their color. They are difficult to heat-treat. Untreated Missouri River Sapphires Rock Creek sapphires are found in abundance and come in a multitude of colors. Smaller in size than Missouri River sapphires, these more rounded sapphires are found in an assortment of colors. Greens, light blues, pinks, yellows, oranges. These stones respond very well to heat-treating producing an amazing array of intense colors. Some of the stones transform into intense blue colors. It is very easy to distinguish these heat-treated stones from natural Yogo sapphires. Sizes for Rock Creek sapphires are generally one carat and less. Stones of three to five carats are rare but seen. Untreated Rock Creek Sapphire Heat treated Rock Creek Sapphires Heat treated Rock Creek Sapphires Heat treated Rock Creek Sapphires Montana Sapphires come in a full spectrum of color Dry Cottonwood sapphires are very similar in nature to the sapphires from Rock Creek. This site is a much smaller deposit than Rock Creek. Heat-treating is the process of heating sapphires to near the melting point to improve color and/or clarity. The vast majority of sapphires and rubies worldwide are enhanced this way. It is a permanent process of changing the stone. Standard heat-treating is generally accepted in the gem industry for the processing of sapphires. The Gem Gallery supports full disclosure of any treating process used on any gemstone. Our natural Yogo sapphires and untreated fancy colored Montana sapphires are completely separated and identified for exactly what they are. The Gem Gallery can offer you the best of these stones, totally natural Yogo sapphires and treated and untreated fancy colored Montana sapphires. Both are treasures from Montana, the Treasure State. Back to top