Degenerate Kali with the Tanjore rosette on the breast / Blank. 6mm, 0.35 grams. Tuticorin mint. Herrli #3.07 var.
Coins with a blank reverse, like this one, are commonly found alongside normal coins in hoards of Colonial fanams. They were either struck with only one die, or (more likely) the reverse die used in striking them was completely worn out and broken (on some such coins very faint traces of the legend can be made out on the reverse).
The Dutch VOC company received the right to strike fanams in Tuticorin from Tanjore. Krause dates these coins to ca.1785-1792. It seems that these coins were struck over a longer period of time, though. The coins are slightly debased, the purity of these coins seems to range from about 14 karats to 18 karats. Rare little coin!