Patent ID: 7637826

Claim:
A multi-piece solid golf ball comprising a core, an envelope encasing the core, an intermediate layer encasing the envelope, and a cover which encases the intermediate layer and has formed on a surface thereof a plurality of dimples, wherein the envelope is composed of at least two layers; the core is formed primarily of a rubber material; the envelope, intermediate layer and cover are each formed primarily of the same or different resin materials; the envelope layers and the intermediate layer have a combined thickness which is at least 5.0 times thicker than the cover; and the core, a Sphere I composed of the core encased by the envelope layers, a Sphere II composed of the core encased by the envelope layers and the intermediate layer, and a Sphere III composed of the core encased by the envelope layers, the intermediate layer and the cover have JIS-C surface hardness relationships therebetween which satisfy the following condition: core surface hardness≦Sphere I surface hardness<Sphere II surface hardness>Sphere III surface hardness, wherein the core hardness increases from the center to the surface of the core, and the hardness difference therebetween in JIS-C units is from 4 to 20.