If you want to quickly open Gmail's address book, you can bookmark google.com/contacts or type the URL in the address bar. Another option is to add a shortcut to the standalone Google Contacts page in Google's app launcher:
1. go to google.com/contacts and sign in
2. click the app launcher icon
3. click "add a shortcut" next to the Contacts icon
4. you can move the icon using drag and drop
You can add similar shortcuts for other Google services: Google Keep, Google Sites, Google Groups, Google Play Music, Webmaster Tools, Patent Search, Google Voice.