If you have a personal GMail account share it with your business account, or create a new Personal calendar if you don't
To share a personal calendar with your business account go to Calendar Settings and select the Calendars tab. You can share this calendar with your business account by adding you email address. This way you can see your personal calendar within your business account and colleagues won't see your personal events (unless you also share with them).
Alternatively you can create a new calendar in your business account by clicking on the drop down arrow next to My calendars and selecting 'Create new calendar'. Call it 'Personal' and use this for your personal events. You can choose to share this with your colleagues in the sharing settings.