How to tell if tanzanite is real or not
Named for its African country of origin, tanzanite is a blue stone used as a substitute for sapphire. Unlike the sapphire, tanzanites are a three-coloured gemstone. They contain three different shades of reds, purples, and blues that are visible to the naked eye.
Synthetic forsterite and blue-violet glass are both sold as tanzanite imitations. Besides inspection from a jeweller, there are steps you can take to determine the authenticity of your tanzanite.
Place stone on white surface. If the stone is mounted, place light below.
- Named for its African country of origin, tanzanite is a blue stone used as a substitute for sapphire.
Hold filter around 36 cm (14 inches) from your eye, right over the stone.
Move filter from side to side, using the strip as a guide. View the stone from several different angles while moving the filter to ensure accurate results.
Compare colours seen with enclosed instruction chart. Imitation tanzanite such as fosterite will show a green colour through the filter. Authentic tanzanite will appear a pinkish-orange colour through the filter.
- There are test kits that include both a filter and dichroscope, many also have a detailed chart with colour descriptions.
- Filters may also be called "Hanneman" filter.
- Using fluorescent or sunlight will cause incorrect readings with a filter.
- Stones that have been set with a dark solid backing may be harder to test using a dichroscope or filter.