The silver cob, issued while Phillip IV was King in Spain, weights 25.8 g. The essayer's mark E is clearly seen twice as well as the date on the one side as 660 and between the pillars as 60. A collector cleared me about the low weight of the coin.
It could be either a shipwreck coin or a good fake. The porosity is regular over the whole coin, making me think it is a wreck-coin. Clearly described at Paoletti's 8 REALES COBS OF POTOSI as type E1 in the page 203. Ensayador Antonio de Ergueta (II periodo) (E).Fecha en ambos lados legible. I send everything through the Chilean Post, registered with tracking.
Due to the pandemic the Chilean Post is serving USA and Europe, but I do not know about other countries. The item "NICE POTOSI PHILIP IV 8 REALES SILVER COB 1660 DOUBLE DATE ESSAYER E ERGUETA" is in sale since Friday, April 2, 2021. This item is in the category "Coins & Paper Money\Coins\ World\South America\Bolivia".The seller is "hobbyteco" and is located in PAINE. This item can be shipped worldwide.