
In today's marketplace a collector can find all sorts of rather "exquisite" shapes of coins including the more "exotic" shapes such as enameled guitars. Throughout the centuries coins were predominately circular in fashion but did include the occasional special square or rectangular flan. Likewise, tokens are found in square, triangular and rectangular forms, and this usually related to the different denominations within a series for easy identification.
During the eighteenth century the hammered coinage of the various kingdoms in South Asia were for the most part rather round but did include the occasional special square issue. Usually the dies were 150% or so larger than the finished strike leaving us with certain coins lacking full inscriptions or dates.
Decades ago my favorite "stop and shop" was with David Laties of Educational Coin Co. then located in Kingston, N.Y. During one visit while sitting at an antique dining room table moved out on a porch for more sunlight David dropped off a rather heavy bag of silver octagonal coins in four different sizes. Obviously my questions were "what and where from?" He replied "try Assam - anĀ old kingdom located near Burma." He also dropped off a copy of the third edition of W. D. Craig's "Coins of the World, 1750-1850" and asked if I could try to sort them out.
After a few hours I was able to sort through the pile and noticed the obverse always had the honorific title of "Shri" or "Shri Shri" starting the inscription. The following characters indicated the ruler's name so there were rows upon rows on the table. Next on the agenda was to sort them by date or no date. What really made it easier is that all the intended inscriptions and date, if intended, were completely within a dotted border carried over to both sides. The numerical characters are only typical to the area.
I found these to be very intriguing and ended up taking about a third of the pile home with me for dealer stock.

For a rather unusual example here is a 1/4 rupee measuring 14 x 14mm struck in the name of Sunyeopha alias Lakshmi Simha who reigned from Saka 1691-1702 (AD 1769-1780). But this particular coin has a problem with the date located on the lower reverse as it is completely retrograde 1696 (reading from right to left) which determines that it is a contemporary forgery.