I bought this from an EBay India seller who listed this as Copper Thirai cash. In Beena Sarasan's book Traversing Travancore through Ages in Coins, similar coin(#67.2 - 1.3grams and 67.3 2.18grams) is listed under title Other Anonymous issues of 17th-18th century in copper and bronze - At least 3 denominations. This coin seems to be the one of lowest denomination with 0.77grams. Only difference is, in the book it is mentioned 'Sun and cresent on biggest denomination' only.
Thira Cash - തിര കാശ്
Regarding the reverse of the coin, the ebay seller mentioned as 'Moon and floral design'. Ms.Sarasan, in her booke mentioned discus or decorated chackra. However, I think this resembles the vaalkannadi or aranmula kannadi - A handmade metal alloy mirror as in the image below.
This is the best Thirai Cash coin which I have in my collection(and hence I used this image with title of this blog). I could not match this with the Mears's catalogue of Thirai Cash. The symbols in this coins were identified though. So, I doubt whether this will be a fake coin. However, there has been a lot of varieties of these coins. So, there is also a possibility that she might have missed this one.