Tanzanite 0.87 cts

Tanzanite’s colour arises from trace amounts of vanadium within the zoisite crystal structure, activated through heat treatment that is now a universal and accepted industry standard. Smaller stones under one carat often display a lighter, more electric blue due to reduced depth of colour transmission through less material — this can actually produce a cleaner, brighter face-up appearance compared to deeply saturated larger stones. Collectors should assess saturation under both incandescent and daylight-equivalent lighting to understand the full chromatic range of any individual piece.

Tanzanite is strongly trichroic, meaning it displays three distinct colours — blue, violet, and burgundy-brown — depending on the axis from which light enters the crystal. Skilled cutters orient the stone so that the blue and violet hues dominate the face-up view, effectively suppressing the less desirable brownish axis. This trichroism is not a colour-change effect in the technical gemological sense, but rotating a loose stone under a single light source will reveal this multi-directional colour behaviour clearly.

Tanzanite registers between 6 and 7 on the Mohs hardness scale and has perfect cleavage in one direction, making it more vulnerable to physical impact than sapphire or ruby. Daily-wear jewellery settings should include protective bezels or low-profile prongs, and the stone should be stored separately to avoid contact abrasion from harder gems. Ultrasonic and steam cleaners are not recommended; warm soapy water with a soft brush remains the safest cleaning method.

Tanzanite’s single-source origin — confined to the Merelani Hills — and the finite nature of the deposit have long supported arguments for its long-term scarcity value, though gemstone markets are never guaranteed. Sub-one-carat stones are generally acquired for wearability and aesthetic merit rather than speculative appreciation, as significant value concentration tends to occur in finely saturated stones above three carats. For a building collector, this size offers a low-risk way to gain practical familiarity with the variety’s colour character and behaviour before committing to higher-value acquisitions.