Golf ball core having medium positive hardness gradient and high surface hardness

1. A golf ball comprising:

a single, unitary, homogeneous core having a surface hardness and a geometric center hardness, the core having an outer diameter of about 1.5 to about 1.62 inches;

an outer cover layer comprising a polyurea, a polyurethane, or a hybrid thereof, and having a first hardness; and

an inner cover layer disposed between the core and the outer cover layer, the inner cover layer having a second hardness greater than the first hardness and within 5 Shore C of the core surface hardness;

wherein the geometric center hardness is about 64 Shore C to about 85 Shore C, and the core surface hardness is greater than 85 Shore C and harder than the geometric center hardness by 5 to 14 Shore C to define a medium positive hardness gradient.

2. The golf ball of claim 1 , wherein the medium positive hardness gradient is 7 to 14 Shore C.

3. The golf ball of claim 2 , wherein the medium positive hardness gradient is 10 to 14 Shore C.

4. The golf ball of claim 1 , wherein the core surface hardness is about 86 to 98 Shore C.

5. The golf ball of claim 4 , wherein the core surface hardness is about 88 to 94 Shore C.

6. The golf ball of claim 1 , wherein the core diameter is about 1.53 to 1.58 inches.

7. The golf ball of claim 1 , wherein the geometric center hardness is about 75 Shore C and the core surface hardness is about 89 Shore C.