Your coin is; 2 Reales , KM# 34.1 Weight 6.4668 g Composition: 0.9030 Silver.
.1964 oz. ASW. Ruler Charles lll. Date 1772G P The coin is from Guatemala found on page 265, of the standard catalog of World Coins, SPAIN, PORTUGAL, and the New World By Chester L Krause ,Clifford Mishler, Colin R Bruce ll, Senior Editor
I have 37 years of books on coins ,Relics,and Marks. Glad to help .I'd just like to come over and touch your brain....