Help Identify This Coin

Certainly it is Spanish colonial era silver or a replica, many of which are posted here for authenticity and identity questions. The reverse design (cross with alternating castles and lions in the angles) is consistent with starting here.

Obviously you can't get a weight, but some size measurement would help tell which denomination. Very roughly, a Spain 1 real coin would be in the range 20 mm diameter, a 2 reales 25 mm, and a 4 reales 30 mm.