shader diffuse color too dark

I know practically nothing about programming shaders, so I need some very simple help. This is a very basic shader for making a solid color with a specular highlight, targeted at iOS. It works fine except that the color that renders is about half of what I specify in the picker. This isn't the case when I use shaders with textures, so I'm pretty sure it's not my scene lighting being too low. How can I increase the brightness on the input color so it's closer to what it looks like in the inspector?

Shader "Solid Color Specularity" { Properties { _Color ("Color", Color) = (1,1,1,1) _Shininess ("Shininess", Range (0.01, 1)) = 0.7 }

 SubShader
 {
     Lighting On
     
     Material
     {
         Diffuse [_Color]
         Ambient [_Color]
         Specular (1,1,1,1)
         Shininess [_Shininess]
     }
     
     Pass {}
 }