I'm looking for the same. I even tried to modified the SecContacts.apk to change the number's color to white. Except for some reason when I push the apk back the phone app keep shutting down. I can open the Contacts app but phone app does not work. I've dabbled in theming before but not on JB so not sure if there's a different process.
*Samsung Galaxy S 4 M919 - Wicked ROM
*HTC One S - ViperOneS ROM
*Asus Eee Pad Transformer TF101 - KatKiss JB 4.3
us 4 16GB - The GN0M3 Project
uS One CyanogenMod 7 temasek's build. (Finally retired)