Genuine ivory can be identified by observing it under black light and looking for certain physical characteristics. Multiple tests are typically performed to verify ivory, because no single test can absolutely guarantee its authenticity.
- Observe the object under black light
Fake ivory substitutes, such as plastics and resins, glow blue or blue-white under black light. Genuine ivory glows white, unless it has been covered with a patina. This test determines whether or not the object is organic or man-made.
- Observe the physical features of the object
Ivory has a natural grain formed by the growth of living tissues. Fake ivory pieces often have a grain as well, but it is evenly spaced and has a clear pattern. Natural ivory grain has no pattern and is not evenly spaced. This test distinguishes true ivory from other bones and glued-together ivory dust.
- Observe the object for Schreger Lines, and measure angles
Elephant ivory has a particular crosshatch pattern observable in the cross-section of a piece of ivory. Measuring the angles of these lines can determine whether the ivory was sourced from extinct animals, such as mammoths, or present-day elephants. Schrenger angles less than 90 degrees indicate an extinct mammoth source, while angles greater than 115 degrees indicate modern-day elephant ivory. For accuracy, measure only the outermost angles, ignoring those in the center. Measure and average at lest five angles for an accurate reading.