How to Identify Fake Tanzanite

Written by aaron kopf
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How to Identify Fake Tanzanite
An image of two tanzanite jewels (tanzanite image by Julianna Olah from

Tanzanite is a recently discovered gemstone from Africa. Brilliant blue in colour with a tinge of purple, tanzanite is rising in popularity with both consumers and jewellers. While tanzanite is not the ideal jewel for daily wear due to its soft composition, if worn occasionally, the blue bauble can last for years. Unfortunately, tanzanite is no exception to the threat of cheaper imitators masquerading as the real deal. Money-conscious consumers can perform their own tests to determine the authenticity of their gem without the need to visit a jeweller.

Skill level:

Things you need

  • Tanzanite filter kit

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    Tanzanite Filter Kit

  1. 1

    Place the white viewing surface included with the tanzanite filter kit on a table. Lay test stones and the gem in question on viewing surface.

  2. 2

    Illuminate the area with a bright incandescent light. The flickering nature of fluorescent light can skew the test results by adding green pigment to the stones. The darker the stones, the closer the light needs to be.

  3. 3

    Observe the test stones through the filter included in the kit. They should appear pinkish-grey in colour.

  4. 4

    Hold the filter up to your eye and examine the gem in question. Consult the table included with the kit to identify the gem.

    Dichroism Test

  1. 1

    Hold the dichroism filter included with the tanzanite filter kit above the gem in question. Be sure to allow at least 14 inches between your eye and the filter.

  2. 2

    Slide the filter side-to-side to examine the stone through each of the adjacent transparent lenses on the dichroism filter.

  3. 3

    Note any changes in colour. Rotate the gem and repeat the process to be sure of your observations.

  4. 4

    Consult the included dichroism chart to identify the gem in question.

Tips and warnings

  • Invite one or more confidants to perform the test. This will decrease the chance of improper identification on your part.
  • These tests are subjective to colour perception. If you want to be absolutely sure of the identify of your gem stone, take it to a certified jeweller that you trust.

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