Rare Ivory: The Elephant Pearl

Elephant pearls are the equivalent of pulp stones in human teeth. They are formed from rounded calcified masses of dentine (ivory) and are recovered from the large softtissue pulps of the continuously growing teeth (tusks) of mammals such as the elephant (recent and fossil).


These rare objects, which are known as Gajamukta (gaja-muthu) are much revered and valued by members of the Buddhist faith - particularly in Sri Lanka. It is commonly believed that the person who possesses a Gajamukta will be very successful in life and could become king. On a more prosaic level, a 16 ct elephant pearl has recently been offered for sale on Ebay for US$15,000.


Identifying elephant pearls requires a mix of observational skill and advanced spectroscopy. As the elephant pearl consists of a rounded mass of dentine, its surface may be patterned by curving growth layers; but the external surface of the elephant pearl will not display an engine-turned surface. This observation allows its ready discrimination from a shaped elephant molar or carved elephant ivory; but will not allow identification of the species of mammal responsible for producing the pearl.


To achieve this discrimination requires use of Raman spectroscopy to determine the relative intensities two specific bands in the suspect elephant pearl’s 1064 nm excited Raman spectra ... vide the protocol established by Edwards et al. (1995, 1997) and detailed in (1995) Spectrochimica Acta. Part A. 51, 2073; (1997) Journal of Molecular Structure. 435, 49-58; and (1997) Spectrochimica. Acta Part A. 53, 2403-2409.


These identifying bands are the 2937 cm-1 band that has been attributed to a specific proteinaceous component of the ivory, and the 960 cm-1 band that been attributed to inorganic 
phosphate in the carbonated hydroxyapatite of the dentine. The identifying I2937 /I960ratios for various ivories are summarised in the following table.


Type of Ivory and I 2940/I 960 Ratio:


African elephant 0.47
Sperm whale 0.45
Asian elephant 0.35
Walrus 0.34
Hippopotamus 0.33
Narwhal 0.16


So,Which is the elephant pearl?

The specimen to the upper right is the true elephant pearl, for it had the I 2940/I 960 ratio of 0.36 that identified its ivory that of the Asiatic elephant. -Grahame Brown (Hobart, Tasmania,19th May 2007)