From the collection of David and Julie Wadsworth - USAID Environmental Project, Manila, The Philippines 1993-97.

From Wikipedia: "Agimat or bertud or anting-anting, is a Filipino word for "amulet" or "charm". Anting-anting is also a Filipino system of magic and sorcery with special use of the above-mentioned talismans, amulets, and charms."  There are agimat for healing, attracting love, protection, removal of hexes, etc.

This anting-anting appears to be Cinco Vocales (five voices) which is used for healing and driving away bad spirits.  It is placed on top of the head of the person to be healed.  On the back is the all-seeing eye of Rome.

It measures approximately 2.25" in diameter and is made of a bronze tone metal.