Someone, specifically one Sap, seems to think the counter stamp was done to reflect reduced value. https://www.coincommunity.com/forum/topic.asp?TOPIC_ID=31711 "I did some searching on Zeno.ru for countermarked Ottoman coins, and found this one very similar to yours, with Arabic letter "B" and the numbers "315" beneath. The experts there say the "B" is short for the Arabic word for "devalued", "315" is indeed the date 1315, and the counterstamp was done in the Dardanelles-Gallipoli region of Turkey, to indicate the coin had a reduced face value.
Thanks. I actually have one of the devalued Dardanelles c/s coins. The one I posted today has a toughra of Abdul Hamid II (I think, it's not very detailed). I have seen images of other coins with that toughra, but in all of those cases it is paired with another c/s for the island of Lesbos. Here is what Dardanelles c/s I have looks like... This is the toughra. It is the same as the one on the host coin. It is probably also some form of devaluation. Abdul Hamid II was the last sultan with any effective control of the Ottoman Empire. https://en.wikipedia.org/wiki/Abdul_Hamid_II
From Sri Lanka or Ceylon to Indonesia with a 2003 500 rupiah (KM 67). The prior dozen or so posts were fantastic. I am really impressed by that beautiful silver Yemen. Thanks to all!