The coin in the image is a silver groat (four pence) of King Henry VI, minted at the Calais mint. The coin is an example of medieval English hammered silver.
Important Details
Dimensions: diameter 26 mm
Material: silver
Weight: 3.39 grams
Ruler: Henry VI, first reign period (1422–1461).
Mint location: Calais.
Issue: The coin belongs to the 'Annulet issue' (circa 1422–1427), identifiable by the specific markings in the legends.
Back Design: In the center sits a long cross pattern that extends through the inscriptions. In each of the four inner corners there is a group of three dots (pellets).
Material and Size: The coin is made of silver and typically has a diameter of about 25 mm and a weight of around 3.92 grams (for a groat, a half groat is lighter).
Inscription: The inner legend on the reverse typically reads 'VILLA CALISIE' (City of Calais), while the outer legend contains 'SIT NOMEN DNI DEI NOSTRI' (Blessed be the name of our Lord God).