Umba Sapphires (English)
Have you heard of Umba sapphires? Unlike sapphires from Sri Lanka (Ceylon), Madagascar, Thailand, or the legendary mines of Kashmir in India, Umba sapphires still remain largely overlooked by major jewellery houses, despite their remarkable potential.
Umba sapphires, from left to right: Emerald cut with princess top ; Cushion mixed cut ; Fancy losange cut ; Long trillion cut ; Pear mixed cut
Discovered in the 1960s near the Umba River in Tanzania, these sapphires offer an extraordinary range of colours, from blue and green to orange, reddish orange, golden yellow, pink, purple, violet, grey, and more. Several factors influence their colour, but one of the main reasons is the presence of chromophore elements such as chromium, iron and titanium. Unlike many coloured sapphires, Umba stones are neither heat-treated nor beryllium-treated, allowing their unique and entirely natural colours to be fully appreciated. Tanzanian sapphires also have another fascinating characteristic: many display a colour change or colour shift depending on the light source. Some stones can appear bluish grey in daylight and shift to purple or even violet under warm or incandescent light, giving you the opportunity to rediscover the same sapphire throughout the day.
Typical inclusions found in an Umba sapphire
At a time when the market increasingly favours “clean” stones, whether eye-clean or loupe-clean, Umba sapphires retain their natural character and carry visible traces of their geological formation. Many different types of inclusions can be found in these gems, but some of the most common include mineral crystals of various shapes and sizes, twinning planes that reflect the crystal’s natural growth, and fingerprints or healed fractures made up of tiny cavities that may contain liquids or gases. These inclusions not only help confirm the natural origin of the sapphire, but also make every stone truly unique. By choosing an Umba sapphire, you are choosing a gemstone with character and individuality, knowing that no other stone will ever be exactly the same.
Umba sapphires, from left to right: Winged Cushion ; Shield cut ; Modern cut ; Modern cut ; Heptagon cut
Do you have a jewellery project in mind, but you are still unsure which gemstone to choose? Umba sapphire is one option I particularly recommend because of its versatility and ability to work beautifully with a wide variety of designs. As mentioned earlier, it comes in a remarkable range of colours and often contains distinctive inclusions that give each stone its own personality. But above all, sapphire has another major advantage: its hardness. Sapphire, like all varieties of corundum, has a hardness of 9 on the Mohs scale, which ranks minerals according to their resistance to scratching. This places it just below diamond, the hardest natural mineral. Thanks to this durability, sapphire is an excellent choice for many types of jewellery. It can be used in pendants, earrings and brooches, as well as pieces that are more exposed to everyday wear and impact, such as bracelets and rings. Its hardness also gives gemcutters greater freedom to explore creative and innovative designs, including unusual fancy shapes, in ways that would be far more difficult with softer or more fragile gemstones such as opal, emerald or fluorite.
Umba sapphires are gemstones with enormous potential, yet they are still relatively unknown to the wider public. If you would like to discover more of them, visit Magus Gems and explore the "Gems" or "Archive" sections. The origin of each sapphire is specified in its individual description.
Looking for an Umba sapphire? Discover our current selection of natural Umba sapphires from Tanzania.
Ludivine Borlot, gemology student